Lost attachment relationship class

[MichaelMorgan4]

Through a little bit of failed testing, I seem to have lost a relationship class between a feature class and its previously related attachment table. The previously set Attachment setting for the feature class is now unchecked. What is the best way to restart that relationship, with all features and attachments intact? If I try to reset Attachments (under the FC's Manage tab), the GDB creates a blank attachment table and a relate class to that. If I try to create a new relate class between FC and attach table, with FC.GlobalID relating to attach.Rel_GlobalID, the GDB comes back with an error 160769, "object class not reg. with GDB, upgrading desktop and workgroup geodatabases not supported."

[AlfredBaldenweck]

Weeeird.

I'd try just renaming the old attachment table, creating a new one, and then appending from the old into the new?

[Robert_LeClair]

In a geodatabase, a relationship class can’t usually be “reconnected” the way a broken map layer source can. If the relationship class is truly missing or its participating tables/classes were renamed/moved, the standard solution is to recreate the relationship class (or revert the datasets to their original names/locations).

There is there this Problem: Related Data from a Relationship Class Not Displayed in ArcGIS Pro document that may or may not assist you.