For reasons unknown, one of my web adaptors "lost" its connection to ArcGIS Server - even though the Server Manager still showed an entry for it.
My only resolution was to delete the registration from ArcGIS Server then and re-register the adaptor.
I was curious if anyone else has seen this happen and, if so, any ideas as to what caused it?
We've been running the current configuration since March with no other problems.
Have you checked if the *ArcGISWebAdaptorAppPool *has read/write access to
the web adaptor config?
There's a bug with web adaptor -
Yes. If that permission issue was the case here, than the problem would be permanent. This is randomly, and intermittently occurring. For no reason, and always happens when there have been no configuration changes.
Looks like this is resolved at 10.3:
BUG-000083324 - ArcGIS Web Adaptor unexpectedly unregisters or loses its configuration and resets to the default or blank configuration