Hi, you need to check the server for server log by setting the log mode to debug. This will establish if the error occur on client before it hits the server or after it hits the server. The log manger is on manager page -> log tab
Arcgis manager url shall look like ,
First go to your feature service url, remove uri until rest/service, https://xxxxx.com/arcgis/[rest/service/xxxxx]
And then go to https://xxx.com/arcgis/manager
UI shall be look like below.
And click query, or you can filter less message by choosing source from your source dropdown [choose your map service]
I understand what you are trying to do with that url above but it actually resolves to an adult site. My poor intern clicked on it much to his chagrin. Maybe edit it?
BTW, I helped Dave look through the logs and we figured out it was the permissions on the feature class in the GDB. Added the web service account and it worked. Thanks for the help.