I have a feature service running on ArcGIS Server (10.5) for which the data resides in a SQL database.
This service is registered in AGOL and then used as the feature service populated by a Survey123 survey.
Users complete surveys using the windows app on a PC.
Everything works as expected for about half of the surveys completed, but the other half fails to send with no error being recorded. It stays in the Outbox with a red exclamation mark. Behaviour is intermittent and inconsistent.
Trawling through the Survey123 logs suggests that applyEdits fails with an error code of "0" and no message being recorded. This leads me to believe that I am losing connection to the service (see attached extract of .log file). Sync is set in the capabilities of the feature service running on ArcGIS Server. There is nothing recorded in the ArcGIS Server logs.
Deleting the surveys that failed to send and re-entering them as a new survey resolves the issue, but this is not practical.
Does anyone else have the same experience? Any thoughts?