My organization has recently been running into a consistent problem downloading Offline Map Areas in the new Collector. This may be similar to other issues users are experiencing but I have not seen anyone post this error message yet.
We are running an ArcGIS Enterprise 10.7.1, and this issue is in Collector App version 20.2.1 Build 2956.
These errors so far have all been occuring on phones and tablets running Android operating systems, although they are happening on iOS too.
I have created a number of offline map areas for use in the field. The map begins to download alright but when the icon is almost complete the following message appears at the bottom of the screen "An error occured downloading the map area". I've managed to download several other, smaller map areas and sync them without issue, but not this one. This specific area is 228.7 MB.
When going into Server Manager Error Logs the most consistent error with every download failure is the following:
|SEVERE||Sep 30, 2020, 1:49:04 PM||Missing layers.|
The web map itself from which the offline map areas are devised does not appear to be missing any layers, and it has been refreshed and packaged prior to a download attempt. Is it a size issue? An instance cap issue with the SyncTools? The Offline Map Areas would be a great functionality for our team but it's been unreliable so far and isn't very explicit in telling users what exactly went wrong.
Any advice or suggestions would be greatly appreciated!