diff --git a/src/Umbraco.Cms.Persistence.SqlServer/Services/SqlServerSyntaxProvider.cs b/src/Umbraco.Cms.Persistence.SqlServer/Services/SqlServerSyntaxProvider.cs
index 7b4feb0a98..9efb97fd6e 100644
--- a/src/Umbraco.Cms.Persistence.SqlServer/Services/SqlServerSyntaxProvider.cs
+++ b/src/Umbraco.Cms.Persistence.SqlServer/Services/SqlServerSyntaxProvider.cs
@@ -1,4 +1,5 @@
 using System.Data;
+using System.Diagnostics.CodeAnalysis;
 using Microsoft.Data.SqlClient;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
diff --git a/src/Umbraco.Core/Configuration/Models/ConnectionStrings.cs b/src/Umbraco.Core/Configuration/Models/ConnectionStrings.cs
index 0642a6171c..f99670d888 100644
--- a/src/Umbraco.Core/Configuration/Models/ConnectionStrings.cs
+++ b/src/Umbraco.Core/Configuration/Models/ConnectionStrings.cs
@@ -30,5 +30,5 @@ public class ConnectionStrings
         set => _connectionString = value.ReplaceDataDirectoryPlaceholder();
     }
 
-    public string ProviderName { get; set; } = DefaultProviderName;
+    public string? ProviderName { get; set; } = DefaultProviderName;
 }
diff --git a/src/Umbraco.Core/DistributedLocking/IDistributedLockingMechanismFactory.cs b/src/Umbraco.Core/DistributedLocking/IDistributedLockingMechanismFactory.cs
index 1bd1cfe206..f2eb80ade0 100644
--- a/src/Umbraco.Core/DistributedLocking/IDistributedLockingMechanismFactory.cs
+++ b/src/Umbraco.Core/DistributedLocking/IDistributedLockingMechanismFactory.cs
@@ -5,5 +5,5 @@ namespace Umbraco.Cms.Core.DistributedLocking;
 /// </summary>
 public interface IDistributedLockingMechanismFactory
 {
-    IDistributedLockingMechanism DistributedLockingMechanism { get; }
+    IDistributedLockingMechanism? DistributedLockingMechanism { get; }
 }
diff --git a/src/Umbraco.Core/Install/Models/DatabaseModel.cs b/src/Umbraco.Core/Install/Models/DatabaseModel.cs
index 37cdcb9610..da2f61fce5 100644
--- a/src/Umbraco.Core/Install/Models/DatabaseModel.cs
+++ b/src/Umbraco.Core/Install/Models/DatabaseModel.cs
@@ -10,7 +10,7 @@ namespace Umbraco.Cms.Core.Install.Models
         public Guid DatabaseProviderMetadataId { get; set; }
 
         [DataMember(Name = "providerName")]
-        public string ProviderName { get; set; }
+        public string? ProviderName { get; set; }
 
         [DataMember(Name = "server")]
         public string Server { get; set; } = null!;
diff --git a/src/Umbraco.Infrastructure/DistributedLocking/DefaultDistributedLockingMechanismFactory.cs b/src/Umbraco.Infrastructure/DistributedLocking/DefaultDistributedLockingMechanismFactory.cs
index 401e399441..2f48a438c0 100644
--- a/src/Umbraco.Infrastructure/DistributedLocking/DefaultDistributedLockingMechanismFactory.cs
+++ b/src/Umbraco.Infrastructure/DistributedLocking/DefaultDistributedLockingMechanismFactory.cs
@@ -12,7 +12,7 @@ public class DefaultDistributedLockingMechanismFactory : IDistributedLockingMech
 {
     private object _lock = new();
     private bool _initialized;
-    private IDistributedLockingMechanism _distributedLockingMechanism;
+    private IDistributedLockingMechanism? _distributedLockingMechanism;
 
     private readonly IOptionsMonitor<GlobalSettings> _globalSettings;
     private readonly IEnumerable<IDistributedLockingMechanism> _distributedLockingMechanisms;
@@ -25,7 +25,7 @@ public class DefaultDistributedLockingMechanismFactory : IDistributedLockingMech
         _distributedLockingMechanisms = distributedLockingMechanisms;
     }
 
-    public IDistributedLockingMechanism DistributedLockingMechanism
+    public IDistributedLockingMechanism? DistributedLockingMechanism
     {
         get
         {
@@ -44,7 +44,7 @@ public class DefaultDistributedLockingMechanismFactory : IDistributedLockingMech
 
         if (!string.IsNullOrEmpty(configured))
         {
-            IDistributedLockingMechanism value = _distributedLockingMechanisms
+            IDistributedLockingMechanism? value = _distributedLockingMechanisms
                 .FirstOrDefault(x => x.GetType().FullName?.EndsWith(configured) ?? false);
 
             if (value == null)
@@ -53,7 +53,7 @@ public class DefaultDistributedLockingMechanismFactory : IDistributedLockingMech
             }
         }
 
-        IDistributedLockingMechanism defaultMechanism = _distributedLockingMechanisms.FirstOrDefault(x => x.Enabled);
+        IDistributedLockingMechanism? defaultMechanism = _distributedLockingMechanisms.FirstOrDefault(x => x.Enabled);
         if (defaultMechanism != null)
         {
             return defaultMechanism;
diff --git a/src/Umbraco.Infrastructure/Logging/Viewer/ExpressionFilter.cs b/src/Umbraco.Infrastructure/Logging/Viewer/ExpressionFilter.cs
index 70c05dc2a4..a1c549add8 100644
--- a/src/Umbraco.Infrastructure/Logging/Viewer/ExpressionFilter.cs
+++ b/src/Umbraco.Infrastructure/Logging/Viewer/ExpressionFilter.cs
@@ -36,11 +36,11 @@ namespace Umbraco.Cms.Core.Logging.Viewer
             else // check if it's a valid expression
             {
                 // If the expression evaluates then make it into a filter
-                if (SerilogExpression.TryCompile(filterExpression, null, customSerilogFunctions, out CompiledExpression compiled, out var error))
+                if (SerilogExpression.TryCompile(filterExpression, null, customSerilogFunctions, out CompiledExpression? compiled, out var error))
                 {
                     filter = evt =>
                     {
-                        LogEventPropertyValue result = compiled(evt);
+                        LogEventPropertyValue? result = compiled(evt);
                         return ExpressionResult.IsTrue(result);
                     };
                 }
@@ -63,12 +63,12 @@ namespace Umbraco.Cms.Core.Logging.Viewer
         private Func<LogEvent, bool>? PerformMessageLikeFilter(string filterExpression)
         {
             var filterSearch = $"@Message like '%{SerilogExpression.EscapeLikeExpressionContent(filterExpression)}%'";
-            if (SerilogExpression.TryCompile(filterSearch, out CompiledExpression compiled, out var error))
+            if (SerilogExpression.TryCompile(filterSearch, out CompiledExpression? compiled, out var error))
             {
                 // `compiled` is a function that can be executed against `LogEvent`s:
                 return evt =>
                 {
-                    LogEventPropertyValue result = compiled(evt);
+                    LogEventPropertyValue? result = compiled(evt);
                     return ExpressionResult.IsTrue(result);
                 };
             }
diff --git a/src/Umbraco.Infrastructure/Logging/Viewer/SerilogLegacyNameResolver.cs b/src/Umbraco.Infrastructure/Logging/Viewer/SerilogLegacyNameResolver.cs
index 0472a8ea16..8e24f40b6c 100644
--- a/src/Umbraco.Infrastructure/Logging/Viewer/SerilogLegacyNameResolver.cs
+++ b/src/Umbraco.Infrastructure/Logging/Viewer/SerilogLegacyNameResolver.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics.CodeAnalysis;
 using Serilog.Expressions;
 
 namespace Umbraco.Cms.Infrastructure.Logging.Viewer
@@ -19,7 +20,7 @@ namespace Umbraco.Cms.Infrastructure.Logging.Viewer
         /// So we can still support the more verbose built in property names such as
         /// Exception, Level, MessageTemplate etc
         /// </summary>
-        public override bool TryResolveBuiltInPropertyName(string alias, out string target)
+        public override bool TryResolveBuiltInPropertyName(string alias, [MaybeNullWhen(false)] out string target)
         {
             target = alias switch
             {
diff --git a/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs b/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
index cf06d38672..ac646d1c67 100644
--- a/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Install/DatabaseBuilder.cs
@@ -71,6 +71,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
             _connectionStrings = connectionStrings;
             _migrationPlanExecutor = migrationPlanExecutor;
             _databaseSchemaCreatorFactory = databaseSchemaCreatorFactory;
+            _databaseProviderMetadata = databaseProviderMetadata;
         }
 
         #region Status
@@ -92,7 +93,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
         /// </summary>
         public bool CanConnect(string? connectionString, string providerName)
         {
-            DbProviderFactory factory = _dbProviderFactoryCreator.CreateFactory(providerName);
+            DbProviderFactory? factory = _dbProviderFactoryCreator.CreateFactory(providerName);
             return DbConnectionExtensions.IsConnectionAvailable(connectionString, factory);
         }
 
@@ -133,7 +134,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
 
         public bool ConfigureDatabaseConnection(DatabaseModel databaseSettings, bool isTrialRun)
         {
-            IDatabaseProviderMetadata providerMeta;
+            IDatabaseProviderMetadata? providerMeta;
 
             // if the database model is null then we will attempt quick install.
             if (databaseSettings == null)
@@ -145,7 +146,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
 
                 databaseSettings = new DatabaseModel
                 {
-                    DatabaseName = providerMeta?.DefaultDatabaseName,
+                    DatabaseName = providerMeta?.DefaultDatabaseName!,
                 };
             }
             else
@@ -162,15 +163,15 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Install
             var connectionString = providerMeta.GenerateConnectionString(databaseSettings);
             var providerName = databaseSettings.ProviderName ?? providerMeta.ProviderName;
 
-            if (providerMeta.RequiresConnectionTest && !CanConnect(connectionString, providerName))
+            if (providerMeta.RequiresConnectionTest && !CanConnect(connectionString, providerName!))
             {
                 return false;
             }
 
             if (!isTrialRun)
             {
-                _configManipulator.SaveConnectionString(connectionString, providerName);
-                Configure(connectionString, providerName, _globalSettings.CurrentValue.InstallMissingDatabase || providerMeta.ForceCreateDatabase);
+                _configManipulator.SaveConnectionString(connectionString!, providerName);
+                Configure(connectionString!, providerName, _globalSettings.CurrentValue.InstallMissingDatabase || providerMeta.ForceCreateDatabase);
             }
 
             return true;
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_0_0/Models/PropertyDataDto80.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_0_0/Models/PropertyDataDto80.cs
index 1755e6c075..69aabd4e21 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_0_0/Models/PropertyDataDto80.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_0_0/Models/PropertyDataDto80.cs
@@ -126,7 +126,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_8_0_0.Models
             return Id == other.Id;
         }
 
-        public override bool Equals(object other)
+        public override bool Equals(object? other)
         {
             return
                 !ReferenceEquals(null, other) // other is not null
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_1_0/ConvertTinyMceAndGridMediaUrlsToLocalLink.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_1_0/ConvertTinyMceAndGridMediaUrlsToLocalLink.cs
index 3f5a966544..e0f2fb3831 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_1_0/ConvertTinyMceAndGridMediaUrlsToLocalLink.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_8_1_0/ConvertTinyMceAndGridMediaUrlsToLocalLink.cs
@@ -51,15 +51,18 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_8_1_0
                     try
                     {
                         var obj = JsonConvert.DeserializeObject<JObject>(value);
-                        var allControls = obj.SelectTokens("$.sections..rows..areas..controls");
+                        var allControls = obj?.SelectTokens("$.sections..rows..areas..controls");
 
-                        foreach (var control in allControls.SelectMany(c => c).OfType<JObject>())
+                        if (allControls is not null)
                         {
-                            var controlValue = control["value"];
-                            if (controlValue?.Type == JTokenType.String)
+                            foreach (var control in allControls.SelectMany(c => c).OfType<JObject>())
                             {
-                                control["value"] = UpdateMediaUrls(mediaLinkPattern, controlValue.Value<string>(), out var controlChanged);
-                                propertyChanged |= controlChanged;
+                                var controlValue = control["value"];
+                                if (controlValue?.Type == JTokenType.String)
+                                {
+                                    control["value"] = UpdateMediaUrls(mediaLinkPattern, controlValue.Value<string>()!, out var controlChanged);
+                                    propertyChanged |= controlChanged;
+                                }
                             }
                         }
 
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/ExternalLoginTokenTable.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/ExternalLoginTokenTable.cs
index 851d986c7c..ee089ad89c 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/ExternalLoginTokenTable.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/ExternalLoginTokenTable.cs
@@ -53,7 +53,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_0_0
             [NullSetting(NullSetting = NullSettings.NotNull)]
             [Index(IndexTypes.UniqueNonClustered, ForColumns = "loginProvider,userOrMemberKey",
                 Name = "IX_" + TableName + "_LoginProvider")]
-            public string LoginProvider { get; set; }
+            public string LoginProvider { get; set; } = null!;
 
             /// <summary>
             ///     Stores the key the provider uses to lookup the login
@@ -63,7 +63,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_0_0
             [NullSetting(NullSetting = NullSettings.NotNull)]
             [Index(IndexTypes.NonClustered, ForColumns = "loginProvider,providerKey",
                 Name = "IX_" + TableName + "_ProviderKey")]
-            public string ProviderKey { get; set; }
+            public string ProviderKey { get; set; } = null!;
 
             [Column("createDate")]
             [Constraint(Default = SystemMethods.CurrentDateTime)]
@@ -75,7 +75,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_0_0
             [Column("userData")]
             [NullSetting(NullSetting = NullSettings.Null)]
             [SpecialDbType(SpecialDbTypes.NTEXT)]
-            public string UserData { get; set; }
+            public string? UserData { get; set; }
         }
     }
 }
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/MigrateLogViewerQueriesFromFileToDb.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/MigrateLogViewerQueriesFromFileToDb.cs
index 2eeca8804d..365c50b3f8 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/MigrateLogViewerQueriesFromFileToDb.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_0_0/MigrateLogViewerQueriesFromFileToDb.cs
@@ -97,7 +97,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_0_0
                 return;
             }
 
-            Database.InsertBulk(logQueriesInFile);
+            Database.InsertBulk(logQueriesInFile!);
 
             Context.AddPostMigration<DeleteLogViewerQueryFile>();
         }
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_2_0/AddUserGroup2NodeTable.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_2_0/AddUserGroup2NodeTable.cs
index 41692825d3..1bb7b71c89 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_2_0/AddUserGroup2NodeTable.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_2_0/AddUserGroup2NodeTable.cs
@@ -22,7 +22,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_2_0
             var allData = Database.Fetch<UserGroup2NodePermissionDto>();
             var toInsert = allData.Select(x => new UserGroup2NodeDto() { NodeId = x.NodeId, UserGroupId = x.UserGroupId }).Distinct(
                 new DelegateEqualityComparer<UserGroup2NodeDto>(
-                (x, y) => x.NodeId == y.NodeId && x.UserGroupId == y.UserGroupId,
+                (x, y) => x?.NodeId == y?.NodeId && x?.UserGroupId == y?.UserGroupId,
                 x => x.NodeId.GetHashCode() + x.UserGroupId.GetHashCode())).ToArray();
             Database.InsertBulk(toInsert);
         }
diff --git a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_3_0/MovePackageXMLToDb.cs b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_3_0/MovePackageXMLToDb.cs
index 3d003eb31d..3173e739a9 100644
--- a/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_3_0/MovePackageXMLToDb.cs
+++ b/src/Umbraco.Infrastructure/Migrations/Upgrade/V_9_3_0/MovePackageXMLToDb.cs
@@ -39,7 +39,7 @@ namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_9_3_0
         private void MigrateCreatedPackageFilesToDb()
         {
             // Load data from file
-            IEnumerable<PackageDefinition> packages = _packagesRepository.GetAll();
+            IEnumerable<PackageDefinition> packages = _packagesRepository.GetAll().WhereNotNull();
             var createdPackageDtos = new List<CreatedPackageSchemaDto>();
             foreach (PackageDefinition package in packages)
             {
diff --git a/src/Umbraco.Infrastructure/Persistence/CustomConnectionStringDatabaseProviderMetadata.cs b/src/Umbraco.Infrastructure/Persistence/CustomConnectionStringDatabaseProviderMetadata.cs
index c9984d69ea..3797d4a433 100644
--- a/src/Umbraco.Infrastructure/Persistence/CustomConnectionStringDatabaseProviderMetadata.cs
+++ b/src/Umbraco.Infrastructure/Persistence/CustomConnectionStringDatabaseProviderMetadata.cs
@@ -23,7 +23,7 @@ public class CustomConnectionStringDatabaseProviderMetadata : IDatabaseProviderM
     public string DefaultDatabaseName => string.Empty;
 
     /// <inheritdoc />
-    public string ProviderName => null;
+    public string? ProviderName => null;
 
     /// <inheritdoc />
     public bool SupportsQuickInstall => false;
@@ -35,7 +35,7 @@ public class CustomConnectionStringDatabaseProviderMetadata : IDatabaseProviderM
     public bool RequiresServer => false;
 
     /// <inheritdoc />
-    public string ServerPlaceholder => null;
+    public string? ServerPlaceholder => null;
 
     /// <inheritdoc />
     public bool RequiresCredentials => false;
@@ -50,6 +50,6 @@ public class CustomConnectionStringDatabaseProviderMetadata : IDatabaseProviderM
     public bool ForceCreateDatabase => false;
 
     /// <inheritdoc />
-    public string GenerateConnectionString(DatabaseModel databaseModel)
+    public string? GenerateConnectionString(DatabaseModel databaseModel)
         => databaseModel.ConnectionString;
 }
diff --git a/src/Umbraco.Infrastructure/Persistence/IDatabaseProviderMetadata.cs b/src/Umbraco.Infrastructure/Persistence/IDatabaseProviderMetadata.cs
index 41baa9c4f8..c766c50d69 100644
--- a/src/Umbraco.Infrastructure/Persistence/IDatabaseProviderMetadata.cs
+++ b/src/Umbraco.Infrastructure/Persistence/IDatabaseProviderMetadata.cs
@@ -34,7 +34,7 @@ public interface IDatabaseProviderMetadata
     /// Gets the database factory provider name.
     /// </summary>
     [DataMember(Name = "providerName")]
-    string ProviderName { get; }
+    string? ProviderName { get; }
 
     /// <summary>
     /// Gets a value indicating whether can be used for one click install.
@@ -58,7 +58,7 @@ public interface IDatabaseProviderMetadata
     /// Gets a value used as input placeholder for server/hostnmae field.
     /// </summary>
     [DataMember(Name = "serverPlaceholder")]
-    string ServerPlaceholder { get; }
+    string? ServerPlaceholder { get; }
 
     /// <summary>
     /// Gets a value indicating whether a username and password are required (in general) to connect to the database
@@ -86,5 +86,5 @@ public interface IDatabaseProviderMetadata
     /// <summary>
     /// Creates a connection string for this provider.
     /// </summary>
-    string GenerateConnectionString(DatabaseModel databaseModel);
+    string? GenerateConnectionString(DatabaseModel databaseModel);
 }
diff --git a/src/Umbraco.Infrastructure/Persistence/NPocoSqlExtensions.cs b/src/Umbraco.Infrastructure/Persistence/NPocoSqlExtensions.cs
index 2d2df7fe4d..f7de532a83 100644
--- a/src/Umbraco.Infrastructure/Persistence/NPocoSqlExtensions.cs
+++ b/src/Umbraco.Infrastructure/Persistence/NPocoSqlExtensions.cs
@@ -75,20 +75,20 @@ namespace Umbraco.Extensions
             return WhereIn(sql, field, values, false, null);
         }
 
-        public static Sql<ISqlContext> WhereIn<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object>> field, Sql<ISqlContext> values, string tableAlias)
+        public static Sql<ISqlContext> WhereIn<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object?>> field, Sql<ISqlContext>? values, string tableAlias)
         {
             return sql.WhereIn(field, values, false, tableAlias);
         }
 
 
-        public static Sql<ISqlContext> WhereLike<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object>> fieldSelector, Sql<ISqlContext> valuesSql)
+        public static Sql<ISqlContext> WhereLike<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object?>> fieldSelector, Sql<ISqlContext>? valuesSql)
         {
             var fieldName = sql.SqlContext.SqlSyntax.GetFieldName(fieldSelector);
-            sql.Where(fieldName + " LIKE (" + valuesSql.SQL + ")", valuesSql.Arguments);
+            sql.Where(fieldName + " LIKE (" + valuesSql?.SQL + ")", valuesSql?.Arguments);
             return sql;
         }
 
-        public static Sql<ISqlContext> WhereLike<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object>> fieldSelector, string likeValue)
+        public static Sql<ISqlContext> WhereLike<TDto>(this Sql<ISqlContext> sql, Expression<Func<TDto, object?>> fieldSelector, string likeValue)
         {
             var fieldName = sql.SqlContext.SqlSyntax.GetFieldName(fieldSelector);
             sql.Where(fieldName + " LIKE ('" + likeValue + "')");
@@ -153,7 +153,7 @@ namespace Umbraco.Extensions
             return WhereIn(sql, fieldSelector, valuesSql, not, null);
         }
 
-        private static Sql<ISqlContext> WhereIn<T>(this Sql<ISqlContext> sql, Expression<Func<T, object?>> fieldSelector, Sql? valuesSql, bool not, string tableAlias)
+        private static Sql<ISqlContext> WhereIn<T>(this Sql<ISqlContext> sql, Expression<Func<T, object?>> fieldSelector, Sql? valuesSql, bool not, string? tableAlias)
         {
             var fieldName = sql.SqlContext.SqlSyntax.GetFieldName(fieldSelector, tableAlias);
             sql.Where(fieldName + (not ? " NOT" : "") +" IN (" + valuesSql?.SQL + ")", valuesSql?.Arguments);
@@ -916,7 +916,7 @@ namespace Umbraco.Extensions
         /// <summary>
         /// Gets fields for a Dto.
         /// </summary>
-        public static string ColumnsForInsert<TDto>(this Sql<ISqlContext> sql, params Expression<Func<TDto, object>>[] fields)
+        public static string ColumnsForInsert<TDto>(this Sql<ISqlContext> sql, params Expression<Func<TDto, object?>>[]? fields)
         {
             if (sql == null) throw new ArgumentNullException(nameof(sql));
             return string.Join(", ", sql.GetColumns(columnExpressions: fields, withAlias: false, forInsert: true));
@@ -1113,7 +1113,7 @@ namespace Umbraco.Extensions
             }
 
             return queryColumns
-                .Select(x => sql.SqlContext.SqlSyntax.GetColumn(sql.SqlContext.DatabaseType, tableName, x.Value.ColumnName, GetAlias(x.Value), referenceName, forInsert: forInsert))
+                .Select(x => sql.SqlContext.SqlSyntax.GetColumn(sql.SqlContext.DatabaseType, tableName, x.Value.ColumnName, GetAlias(x.Value)!, referenceName, forInsert: forInsert))
                 .ToArray();
         }
 
diff --git a/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/RelationRepository.cs b/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/RelationRepository.cs
index dde11ead71..6aeb967361 100644
--- a/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/RelationRepository.cs
+++ b/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/RelationRepository.cs
@@ -469,27 +469,27 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
         public Guid ChildNodeKey { get; set; }
 
         [Column(Name = "nodeName")]
-        public string ChildNodeName { get; set; }
+        public string? ChildNodeName { get; set; }
 
         [Column(Name = "nodeObjectType")]
         public Guid ChildNodeObjectType { get; set; }
 
         [Column(Name = "contentTypeIcon")]
-        public string ChildContentTypeIcon { get; set; }
+        public string? ChildContentTypeIcon { get; set; }
 
         [Column(Name = "contentTypeAlias")]
-        public string ChildContentTypeAlias { get; set; }
+        public string? ChildContentTypeAlias { get; set; }
 
         [Column(Name = "contentTypeName")]
-        public string ChildContentTypeName { get; set; }
+        public string? ChildContentTypeName { get; set; }
 
 
 
         [Column(Name = "relationTypeName")]
-        public string RelationTypeName { get; set; }
+        public string? RelationTypeName { get; set; }
 
         [Column(Name = "relationTypeAlias")]
-        public string RelationTypeAlias { get; set; }
+        public string? RelationTypeAlias { get; set; }
 
         [Column(Name = "relationTypeIsDependency")]
         public bool RelationTypeIsDependency { get; set; }
diff --git a/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/TrackedReferencesRepository.cs b/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/TrackedReferencesRepository.cs
index d92f0903f1..ae1939973f 100644
--- a/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/TrackedReferencesRepository.cs
+++ b/src/Umbraco.Infrastructure/Persistence/Repositories/Implement/TrackedReferencesRepository.cs
@@ -24,7 +24,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
         public IEnumerable<RelationItem> GetPagedItemsWithRelations(int[] ids, long pageIndex, int pageSize,
             bool filterMustBeIsDependency, out long totalRecords)
         {
-            var sql = _scopeAccessor.AmbientScope.Database.SqlContext.Sql().Select(
+            var sql = _scopeAccessor.AmbientScope?.Database.SqlContext.Sql().Select(
                     "[pn].[id] as nodeId",
                     "[pn].[uniqueId] as nodeKey",
                     "[pn].[text] as nodeName",
@@ -46,43 +46,43 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
 
             if (ids.Any())
             {
-                sql = sql.Where<NodeDto>(x => ids.Contains(x.NodeId), "pn");
+                sql = sql?.Where<NodeDto>(x => ids.Contains(x.NodeId), "pn");
             }
 
             if (filterMustBeIsDependency)
             {
-                sql = sql.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
+                sql = sql?.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
             }
 
             // Ordering is required for paging
-            sql = sql.OrderBy<RelationTypeDto>(x => x.Alias);
+            sql = sql?.OrderBy<RelationTypeDto>(x => x.Alias);
 
-            var pagedResult = _scopeAccessor.AmbientScope.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
-            totalRecords = Convert.ToInt32(pagedResult.TotalItems);
+            var pagedResult = _scopeAccessor.AmbientScope?.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
+            totalRecords = Convert.ToInt32(pagedResult?.TotalItems);
 
-            return pagedResult.Items.Select(MapDtoToEntity);
+            return pagedResult?.Items.Select(MapDtoToEntity) ?? Enumerable.Empty<RelationItem>();
         }
 
         public IEnumerable<RelationItem> GetPagedDescendantsInReferences(int parentId, long pageIndex, int pageSize, bool filterMustBeIsDependency,
             out long totalRecords)
         {
-            var syntax = _scopeAccessor.AmbientScope.Database.SqlContext.SqlSyntax;
+            var syntax = _scopeAccessor.AmbientScope?.Database.SqlContext.SqlSyntax;
 
             // Gets the path of the parent with ",%" added
-            var subsubQuery = _scopeAccessor.AmbientScope.Database.SqlContext.Sql()
-                .Select(syntax.GetConcat("[node].[path]", "',%'"))
+            var subsubQuery = _scopeAccessor.AmbientScope?.Database.SqlContext.Sql()
+                .Select(syntax?.GetConcat("[node].[path]", "',%'"))
                 .From<NodeDto>("node")
                 .Where<NodeDto>(x => x.NodeId == parentId, "node");
 
 
             // Gets the descendants of the parent node
-            Sql<ISqlContext> subQuery = _scopeAccessor.AmbientScope.Database.SqlContext.Sql()
+            Sql<ISqlContext>? subQuery = _scopeAccessor.AmbientScope?.Database.SqlContext.Sql()
                 .Select<NodeDto>(x => x.NodeId)
                 .From<NodeDto>()
                 .WhereLike<NodeDto>(x => x.Path, subsubQuery);
 
             // Get all relations where parent is in the sub query
-            var sql = _scopeAccessor.AmbientScope.Database.SqlContext.Sql().Select(
+            var sql = _scopeAccessor.AmbientScope?.Database.SqlContext.Sql().Select(
                     "[pn].[id] as nodeId",
                     "[pn].[uniqueId] as nodeKey",
                     "[pn].[text] as nodeName",
@@ -101,23 +101,23 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
                 .LeftJoin<ContentDto>("c").On<NodeDto, ContentDto>((left, right) => left.NodeId == right.NodeId, aliasLeft:"pn", aliasRight:"c")
                 .LeftJoin<ContentTypeDto>("ct").On<ContentDto, ContentTypeDto>((left, right) => left.ContentTypeId == right.NodeId, aliasLeft:"c",  aliasRight:"ct")
                 .LeftJoin<NodeDto>("ctn").On<ContentTypeDto, NodeDto>((left, right) => left.NodeId == right.NodeId, aliasLeft:"ct",  aliasRight:"ctn")
-                .WhereIn((System.Linq.Expressions.Expression<Func<NodeDto, object>>)(x => x.NodeId), subQuery, "pn");
+                .WhereIn((System.Linq.Expressions.Expression<Func<NodeDto, object?>>)(x => x.NodeId), subQuery, "pn");
             if (filterMustBeIsDependency)
             {
-                sql = sql.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
+                sql = sql?.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
             }
             // Ordering is required for paging
-            sql = sql.OrderBy<RelationTypeDto>(x => x.Alias);
+            sql = sql?.OrderBy<RelationTypeDto>(x => x.Alias);
 
-            var pagedResult = _scopeAccessor.AmbientScope.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
-            totalRecords = Convert.ToInt32(pagedResult.TotalItems);
+            var pagedResult = _scopeAccessor.AmbientScope?.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
+            totalRecords = Convert.ToInt32(pagedResult?.TotalItems);
 
-            return pagedResult.Items.Select(MapDtoToEntity);
+            return pagedResult?.Items.Select(MapDtoToEntity) ?? Enumerable.Empty<RelationItem>();
         }
 
         public IEnumerable<RelationItem> GetPagedRelationsForItems(int[] ids, long pageIndex, int pageSize, bool filterMustBeIsDependency, out long totalRecords)
         {
-            var sql = _scopeAccessor.AmbientScope.Database.SqlContext.Sql().Select(
+            var sql = _scopeAccessor.AmbientScope?.Database.SqlContext.Sql().Select(
                     "[cn].[id] as nodeId",
                     "[cn].[uniqueId] as nodeKey",
                     "[cn].[text] as nodeName",
@@ -139,21 +139,21 @@ namespace Umbraco.Cms.Infrastructure.Persistence.Repositories.Implement
 
             if (ids.Any())
             {
-                sql = sql.Where<NodeDto>(x => ids.Contains(x.NodeId), "pn");
+                sql = sql?.Where<NodeDto>(x => ids.Contains(x.NodeId), "pn");
             }
 
             if (filterMustBeIsDependency)
             {
-                sql = sql.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
+                sql = sql?.Where<RelationTypeDto>(rt => rt.IsDependency, "umbracoRelationType");
             }
 
             // Ordering is required for paging
-            sql = sql.OrderBy<RelationTypeDto>(x => x.Alias);
+            sql = sql?.OrderBy<RelationTypeDto>(x => x.Alias);
 
-            var pagedResult = _scopeAccessor.AmbientScope.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
-            totalRecords = Convert.ToInt32(pagedResult.TotalItems);
+            var pagedResult = _scopeAccessor.AmbientScope?.Database.Page<RelationItemDto>(pageIndex + 1, pageSize, sql);
+            totalRecords = Convert.ToInt32(pagedResult?.TotalItems);
 
-            return pagedResult.Items.Select(MapDtoToEntity);
+            return pagedResult?.Items.Select(MapDtoToEntity) ?? Enumerable.Empty<RelationItem>();
         }
 
         private RelationItem MapDtoToEntity(RelationItemDto dto)
diff --git a/src/Umbraco.Infrastructure/Persistence/SqlSyntax/ISqlSyntaxProvider.cs b/src/Umbraco.Infrastructure/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
index 316758a6f8..aeb0f51c4c 100644
--- a/src/Umbraco.Infrastructure/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
+++ b/src/Umbraco.Infrastructure/Persistence/SqlSyntax/ISqlSyntaxProvider.cs
@@ -16,7 +16,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
     /// </summary>
     public interface ISqlSyntaxProvider
     {
-        DatabaseType GetUpdatedDatabaseType(DatabaseType current, string connectionString);
+        DatabaseType GetUpdatedDatabaseType(DatabaseType current, string? connectionString);
 
         string ProviderName { get; }
 
@@ -27,7 +27,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
         string GetStringColumnWildcardComparison(string column, int paramIndex, TextColumnType columnType);
         string GetConcat(params string[] args);
 
-        string GetColumn(DatabaseType dbType, string tableName, string columnName, string columnAlias, string referenceName = null, bool forInsert = false);
+        string GetColumn(DatabaseType dbType, string tableName, string columnName, string columnAlias, string? referenceName = null, bool forInsert = false);
 
         string GetQuotedTableName(string? tableName);
         string GetQuotedColumnName(string? columnName);
@@ -140,7 +140,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
         bool TryGetDefaultConstraint(IDatabase db, string? tableName, string columnName, [MaybeNullWhen(false)] out string constraintName);
 
 
-        string GetFieldNameForUpdate<TDto>(Expression<Func<TDto, object>> fieldSelector, string tableAlias = null);
+        string GetFieldNameForUpdate<TDto>(Expression<Func<TDto, object?>> fieldSelector, string? tableAlias = null);
 
         /// <summary>
         /// Appends the relevant ForUpdate hint.
@@ -158,8 +158,8 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
         Sql<ISqlContext>.SqlJoinClause<ISqlContext> LeftJoinWithNestedJoin<TDto>(
             Sql<ISqlContext> sql,
             Func<Sql<ISqlContext>, Sql<ISqlContext>> nestedJoin,
-            string alias = null);
+            string? alias = null);
 
-        IDictionary<Type, IScalarMapper> ScalarMappers { get; }
+        IDictionary<Type, IScalarMapper>? ScalarMappers { get; }
     }
 }
diff --git a/src/Umbraco.Infrastructure/Persistence/SqlSyntax/SqlSyntaxProviderBase.cs b/src/Umbraco.Infrastructure/Persistence/SqlSyntax/SqlSyntaxProviderBase.cs
index da97287493..b2bbd4ac5b 100644
--- a/src/Umbraco.Infrastructure/Persistence/SqlSyntax/SqlSyntaxProviderBase.cs
+++ b/src/Umbraco.Infrastructure/Persistence/SqlSyntax/SqlSyntaxProviderBase.cs
@@ -139,7 +139,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
             return dbTypeMap.Create();
         }
 
-        public virtual DatabaseType GetUpdatedDatabaseType(DatabaseType current, string connectionString) => current;
+        public virtual DatabaseType GetUpdatedDatabaseType(DatabaseType current, string? connectionString) => current;
 
         public abstract string ProviderName { get; }
 
@@ -222,7 +222,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
 
         public virtual string GetSpecialDbType(SpecialDbType dbType, int customSize) => $"{GetSpecialDbType(dbType)}({customSize})";
 
-        public virtual string GetColumn(DatabaseType dbType, string tableName, string columnName, string columnAlias, string referenceName = null, bool forInsert = false)
+        public virtual string GetColumn(DatabaseType dbType, string tableName, string columnName, string columnAlias, string? referenceName = null, bool forInsert = false)
         {
             tableName = GetQuotedTableName(tableName);
             columnName = GetQuotedColumnName(columnName);
@@ -263,16 +263,16 @@ namespace Umbraco.Cms.Infrastructure.Persistence.SqlSyntax
 
         public abstract bool TryGetDefaultConstraint(IDatabase db, string? tableName, string columnName, [MaybeNullWhen(false)] out string constraintName);
 
-        public virtual string GetFieldNameForUpdate<TDto>(Expression<Func<TDto, object>> fieldSelector, string tableAlias = null) => this.GetFieldName(fieldSelector, tableAlias);
+        public virtual string GetFieldNameForUpdate<TDto>(Expression<Func<TDto, object?>> fieldSelector, string? tableAlias = null) => this.GetFieldName(fieldSelector, tableAlias);
 
         public virtual Sql<ISqlContext> InsertForUpdateHint(Sql<ISqlContext> sql) => sql;
 
         public virtual Sql<ISqlContext> AppendForUpdateHint(Sql<ISqlContext> sql) => sql;
 
-        public abstract Sql<ISqlContext>.SqlJoinClause<ISqlContext> LeftJoinWithNestedJoin<TDto>(Sql<ISqlContext> sql, Func<Sql<ISqlContext>, Sql<ISqlContext>> nestedJoin, string alias = null);
+        public abstract Sql<ISqlContext>.SqlJoinClause<ISqlContext> LeftJoinWithNestedJoin<TDto>(Sql<ISqlContext> sql, Func<Sql<ISqlContext>, Sql<ISqlContext>> nestedJoin, string? alias = null);
 
 
-        public virtual IDictionary<Type, IScalarMapper> ScalarMappers => null;
+        public virtual IDictionary<Type, IScalarMapper>? ScalarMappers => null;
 
         public virtual bool DoesTableExist(IDatabase db, string tableName) => GetTablesInSchema(db).Contains(tableName);
 
diff --git a/src/Umbraco.Infrastructure/Persistence/UmbracoDatabase.cs b/src/Umbraco.Infrastructure/Persistence/UmbracoDatabase.cs
index 4dd0c20aed..83ab603a35 100644
--- a/src/Umbraco.Infrastructure/Persistence/UmbracoDatabase.cs
+++ b/src/Umbraco.Infrastructure/Persistence/UmbracoDatabase.cs
@@ -342,7 +342,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence
                 return base.ExecuteScalar<T>(sql, commandType, args);
             }
 
-            if (!SqlContext.SqlSyntax.ScalarMappers.TryGetValue(typeof(T), out IScalarMapper mapper))
+            if (!SqlContext.SqlSyntax.ScalarMappers.TryGetValue(typeof(T), out IScalarMapper? mapper))
             {
                 return base.ExecuteScalar<T>(sql, commandType, args);
             }
diff --git a/src/Umbraco.Infrastructure/Persistence/UmbracoDatabaseFactory.cs b/src/Umbraco.Infrastructure/Persistence/UmbracoDatabaseFactory.cs
index 137f4ddb62..72daab4646 100644
--- a/src/Umbraco.Infrastructure/Persistence/UmbracoDatabaseFactory.cs
+++ b/src/Umbraco.Infrastructure/Persistence/UmbracoDatabaseFactory.cs
@@ -51,7 +51,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence
         private bool _upgrading;
         private bool _initialized;
 
-        private ConnectionStrings _umbracoConnectionString;
+        private ConnectionStrings? _umbracoConnectionString;
 
         private DbProviderFactory? _dbProviderFactory = null;
 
@@ -239,7 +239,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence
                 cfg.UsingDatabase(CreateDatabaseInstance) // creating UmbracoDatabase instances
                     .WithFluentConfig(config); // with proper configuration
 
-                foreach (IProviderSpecificInterceptor interceptor in _dbProviderFactoryCreator.GetProviderSpecificInterceptors(ProviderName))
+                foreach (IProviderSpecificInterceptor interceptor in _dbProviderFactoryCreator.GetProviderSpecificInterceptors(ProviderName!))
                 {
                     cfg.WithInterceptor(interceptor);
                 }
@@ -274,6 +274,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence
             {
                 return null;
             }
+
             return new UmbracoDatabase(
                 ConnectionString,
                 SqlContext,
@@ -282,6 +283,7 @@ namespace Umbraco.Cms.Infrastructure.Persistence
                 _bulkSqlInsertProvider,
                 _databaseSchemaCreatorFactory,
                 _pocoMappers);
+        }
 
         protected override void DisposeResources()
         {
diff --git a/src/Umbraco.Infrastructure/Runtime/FileSystemMainDomLock.cs b/src/Umbraco.Infrastructure/Runtime/FileSystemMainDomLock.cs
index c4cbcef588..37e962a222 100644
--- a/src/Umbraco.Infrastructure/Runtime/FileSystemMainDomLock.cs
+++ b/src/Umbraco.Infrastructure/Runtime/FileSystemMainDomLock.cs
@@ -19,8 +19,8 @@ namespace Umbraco.Cms.Infrastructure.Runtime
         private readonly string _lockFilePath;
         private readonly string _releaseSignalFilePath;
 
-        private FileStream _lockFileStream;
-        private Task _listenForReleaseSignalFileTask;
+        private FileStream? _lockFileStream;
+        private Task? _listenForReleaseSignalFileTask;
 
         public FileSystemMainDomLock(
             ILogger<FileSystemMainDomLock> logger,
diff --git a/src/Umbraco.Infrastructure/Scoping/Scope.cs b/src/Umbraco.Infrastructure/Scoping/Scope.cs
index d7a67f1db8..008556225b 100644
--- a/src/Umbraco.Infrastructure/Scoping/Scope.cs
+++ b/src/Umbraco.Infrastructure/Scoping/Scope.cs
@@ -1083,7 +1083,7 @@ namespace Umbraco.Cms.Core.Scoping
             Guid instanceId,
             ref Dictionary<Guid, Dictionary<int, int>>? locks,
             ref HashSet<int>? locksSet,
-            Action<int, TimeSpan> obtainLock,
+            Action<int, TimeSpan?> obtainLock,
             TimeSpan? timeout,
             int lockId)
         {