@ColinLawrence I've received the error both while conducting a simple attribute edit on the parent feature (water meter point layer) and while trying to submit a child record in the related work history table. A record is technically added to the child table after the user agrees to discard their edits on the related table. The edit still commits, a new table record is created, and any attribute rules that are supposed to fire are fired. The relationship type between the water meter layer and the work history table is simple, the cardinality is one to many, and the keyfields are: GlobalID (origin primary key) and Related_Asset (origin foreign key).
All of this was working the day before the Field Maps app was updated and has been working for the past 4+ years.
Looking at the logs, I noticed when we were getting the error message in Field Maps, the timestamps correlated to this error in the logs: [EDITING] stopEditing failed with error: ArcGISError(code: 1019, description: "SQLite constraint violation.", details: "SQLite: 19\nAbort due to constraint violation")