I installed Portal for ArcGIS Security 2026 Update 2 Patch last week. I immediately notices a huge spike in error logs as well as CPU and RAM usage on our GIS servers. We eventually tracked down that basically all of our service account permissions has been removed on our ArcGIS Server and Portal servers. It was enough errors to crash ArcGIS Server before we could hunt down the last folders that needed permissions restored.
So just an FYI. We started seeing lots of missing thumbnail errors, Error in checking static data for service: xyzxyzxyz - Service not found Rest. There were some others in there as well causing more severe errors.
We are still monitoring everything to see if the last fix yesterday afternoon fixed it completely.
