Error : Update customfields by API, API server error

Shopware 6 (English)
1

When I want to update the value of a customfield I get the following error:

{„errors“:[{„code“:„0“,„status“:„500“,„title“:„Internal Server Error“,„detail“:"Shopware\Core\System\CustomField\CustomFieldService::getCustomField(): Argument #1 ($attributeName) must be of type string, int given,

I seems like the internal function still works with the old integer instead of the new uuid’s.

I use this simple code, to update a custom field:

{
„customFields“: {
„your_custom_field_key“: „value“
}
}

Any idea?