Save your hide by restoring a SharePoint farm configuration
I had the scare of the week last night. I was doing some pre-approved SharePoint farm cleanup. Part of that was removing some Farm Solutions (WSPs). The Retract of the solution partially failed, and hosed Central Admin (ouch).
Last time I had this, the uninstall of UMT software left a dozen dangling references in all Web.Configs that I cleaned up by hand. Those caused workflows to all stop. This time, I was getting security and page rendering errors.
Good thing we had done a backupSPFarm recently with ConfigurationOnly option.
Once the restore was done, Central Admin appeared to behave erratically. This was simply the farm sync’ing up, with a series of IISResets associated with feature re-deployment.