diff --git a/src/Umbraco.Core/Migrations/Upgrade/UmbracoPlan.cs b/src/Umbraco.Core/Migrations/Upgrade/UmbracoPlan.cs
index eeaf7533a9..5b0838573e 100644
--- a/src/Umbraco.Core/Migrations/Upgrade/UmbracoPlan.cs
+++ b/src/Umbraco.Core/Migrations/Upgrade/UmbracoPlan.cs
@@ -137,6 +137,7 @@ namespace Umbraco.Core.Migrations.Upgrade
             // resume at {290C18EE-B3DE-4769-84F1-1F467F3F76DA}...
 
             Chain<DropTaskTables>("{6A2C7C1B-A9DB-4EA9-B6AB-78E7D5B722A7}");
+            Chain<FixLockTablePrimaryKey>("{77874C77-93E5-4488-A404-A630907CEEF0}");
 
             //FINAL
 
diff --git a/src/Umbraco.Core/Migrations/Upgrade/V_8_0_0/FixLockTablePrimaryKey.cs b/src/Umbraco.Core/Migrations/Upgrade/V_8_0_0/FixLockTablePrimaryKey.cs
new file mode 100644
index 0000000000..fbb233927b
--- /dev/null
+++ b/src/Umbraco.Core/Migrations/Upgrade/V_8_0_0/FixLockTablePrimaryKey.cs
@@ -0,0 +1,23 @@
+using System.Linq;
+
+namespace Umbraco.Core.Migrations.Upgrade.V_8_0_0
+{
+    public class FixLockTablePrimaryKey : MigrationBase
+    {
+        public FixLockTablePrimaryKey(IMigrationContext context)
+            : base(context)
+        { }
+
+        public override void Migrate()
+        {
+            // at some point, the KeyValueService dropped the PK and failed to re-create it,
+            // so the PK is gone - make sure we have one, and create if needed
+
+            var constraints = SqlSyntax.GetConstraintsPerTable(Database);
+            var exists = constraints.Any(x => x.Item2 == "PK_umbracoLock");
+
+            if (!exists)
+                Create.PrimaryKey("PK_umbracoLock").OnTable(Constants.DatabaseSchema.Tables.Lock).Column("id").Do();
+        }
+    }
+}
diff --git a/src/Umbraco.Core/Umbraco.Core.csproj b/src/Umbraco.Core/Umbraco.Core.csproj
index aef18e59db..6951a9e17a 100644
--- a/src/Umbraco.Core/Umbraco.Core.csproj
+++ b/src/Umbraco.Core/Umbraco.Core.csproj
@@ -357,6 +357,7 @@
     <Compile Include="Migrations\Upgrade\V_8_0_0\AddVariationTables2.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\DataTypeMigration.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\DropTaskTables.cs" />
+    <Compile Include="Migrations\Upgrade\V_8_0_0\FixLockTablePrimaryKey.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\LanguageColumns.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\PropertyEditorsMigration.cs" />
     <Compile Include="Migrations\Upgrade\V_8_0_0\RefactorMacroColumns.cs" />