When attempting to upload changes to your creatives (new or edit) via bulk sheet, the operation will fail and you may be presented with the following error message (or a variation thereof):

Property headline is not valid. The following constraint violations
were detected MaxLengthWithSubstitutionValidator:

What Causes The Issue?

This error occurs when you are trying to bulk create or edit creatives and you exceed the allowed number of characters in a creative headline. The maximum number of characters in usually 30.

How To Fix The Issue

To solve this issue, you must ensure that none of the creatives you are trying to upload exceed the maximum character limit of 30. Once the number of characters has been reduced, the upload should succeed.