sqlalchemy.orm.exc.StaleDataError

An operation encountered database state that is unaccounted for.

Conditions which cause this to happen include:

• A flush may have attempted to update or delete rows and an unexpected number of rows were matched during the UPDATE or DELETE statement. Note that when version_id_col is used, rows in UPDATE or DELETE statements are also matched against the current known version identifier.
• A mapped object with version_id_col was refreshed, and the version number coming back from the database does not match that of the object itself.
• A object is detached from its parent object, however the object was previously attached to a different parent identity which was garbage collected, and a decision cannot be made if the new parent was really the most recent "parent".