for a specific feature service I spontaneously cannot enable Sync for offline use with Collector.
When I select "enable sync.." and attempt to save the service setting I get an error "cannot update service definition".
I was able to enable off-line use when I first published the service.
Is this data ready to be a sync enabled feature service?
To use the sync capability, all the data in the feature service must be from an enterprise geodatabase. Also, you must prepare the data so it can be used offline and, if required, synchronized through the feature service when you have connectivity.
The data you use in a sync-enabled feature service can be either nonversioned with archiving enabled or, if your organization's data or workflows require it, the data can be versioned.
Be aware that you can only enable the sync capability when all the data in the map is configured exactly the same; you cannot have a mix of versioned and nonversioned data.
Is this a hosted feature service or an ArcGIS Enterprise Feature Service?
If it's a Hosted Feature Service please get in contact with support to see what is causing the issue.
This was a hosted feature on AGOL.
I've also couldn't retrieve the feature properties correctly, or load it into a map, suggesting that something was corrupted. I've since over-written the service from Desktop to restore the data.