I have a documenttype where customer now found out they want to change one element to not varyByCulture. They already added loads of content, but while translating they found out this field should not varybyculture.

When I now try to change the element in backend, I get a long exception

at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at Umbraco.Core.Persistence.Repositories.Implement.ContentTypeRepositoryBase`1.RenormalizeDocumentEditedFlags(IReadOnlyCollection`1 propertyTypeIds, IReadOnlyCollection`1 contentTypeIds) in D:\a\1\s\src\Umbraco.Core\Persistence\Repositories\Implement\ContentTypeRepositoryBase.cs:line 1099
   at Umbraco.Core.Persistence.Repositories.Implement.ContentTypeRepositoryBase`1.MovePropertyTypeVariantData(IDictionary`2 propertyTypeChanges, IEnumerable`1 impacted) in D:\a\1\s\src\Umbraco.Core\Persistence\Repositories\Implement\ContentTypeRepositoryBase.cs:line 685
   at Umbraco.Core.Persistence.Repositories.Implement.ContentTypeRepositoryBase`1.PersistUpdatedBaseContentType(IContentTypeComposition entity) in D:\a\1\s\src\Umbraco.Core\Persistence\Repositories\Implement\ContentTypeRepositoryBase.cs:line 500
   at Umbraco.Core.Persistence.Repositories.Implement.ContentTypeRepository.PersistUpdatedItem(IContentType entity) in D:\a\1\s\src\Umbraco.Core\Persistence\Repositories\Implement\ContentTypeRepository.cs:line 290
   at ....

which narrows down to:

An item with the same key has already been added.

How can I change this one element, without having to recreate all content for that element, which is quite a lot!

I also tried to do that with uSync, also no success!

Best, Gerhard