Add the default date-with-time configuration if missing

src/Umbraco.Infrastructure/Migrations/Upgrade/UmbracoPlan.cs

@@ -88,5 +88,8 @@ protected virtual void DefinePlan()
         // To 14.1.0
         To<V_14_1_0.MigrateRichTextConfiguration>("{FEF2DAF4-5408-4636-BB0E-B8798DF8F095}");
         To<V_14_1_0.MigrateOldRichTextSeedConfiguration>("{A385C5DF-48DC-46B4-A742-D5BB846483BC}");
+
+        // To 14.2.0
+        To<V_14_2_0.AddMissingDateTimeConfiguration>("{20ED404C-6FF9-4F91-8AC9-2B298E0002EB}");
     }
 }

src/Umbraco.Infrastructure/Migrations/Upgrade/V_14_2_0/AddMissingDateTimeConfiguration.cs

@@ -0,0 +1,50 @@
+using NPoco;
+using Umbraco.Cms.Core;
+using Umbraco.Cms.Core.Serialization;
+using Umbraco.Cms.Infrastructure.Persistence;
+using Umbraco.Cms.Infrastructure.Persistence.Dtos;
+using Umbraco.Extensions;
+
+namespace Umbraco.Cms.Infrastructure.Migrations.Upgrade.V_14_2_0;
+
+public class AddMissingDateTimeConfiguration : MigrationBase
+{
+    private readonly IConfigurationEditorJsonSerializer _configurationEditorJsonSerializer;
+
+    public AddMissingDateTimeConfiguration(IMigrationContext context, IConfigurationEditorJsonSerializer configurationEditorJsonSerializer)
+        : base(context)
+        => _configurationEditorJsonSerializer = configurationEditorJsonSerializer;
+
+    protected override void Migrate()
+    {
+        Sql<ISqlContext> sql = Sql()
+            .Select<DataTypeDto>()
+            .From<DataTypeDto>()
+            .Where<DataTypeDto>(dto =>
+                dto.NodeId == Constants.DataTypes.DateTime
+                && dto.EditorAlias.Equals(Constants.PropertyEditors.Aliases.DateTime));
+
+        DataTypeDto? dataTypeDto = Database.FirstOrDefault<DataTypeDto>(sql);
+        if (dataTypeDto is null)
+        {
+            return;
+        }
+
+        Dictionary<string, object> configurationData = dataTypeDto.Configuration.IsNullOrWhiteSpace()
+            ? new Dictionary<string, object>()
+            : _configurationEditorJsonSerializer
+                  .Deserialize<Dictionary<string, object?>>(dataTypeDto.Configuration)?
+                  .Where(item => item.Value is not null)
+                  .ToDictionary(item => item.Key, item => item.Value!)
+              ?? new Dictionary<string, object>();
+
+        // only proceed with the migration if the data-type has no format assigned
+        if (configurationData.TryAdd("format", "YYYY-MM-DD HH:mm:ss") is false)
+        {
+            return;
+        }
+
+        dataTypeDto.Configuration = _configurationEditorJsonSerializer.Serialize(configurationData);
+        Database.Update(dataTypeDto);
+    }
+}