For anyone who comes across this message: The UI Behavior is: Any Add-on Builder Setup page will spin and spin and spin (e.g., it will load the overall Splunk UI, but when you try to go to the configuration page, the main panel will show the normal loading icon but it won't go away). The back-end behavior is: you'll see a 500 error and the stack trace below.  Root Cause: a passwords.conf that cannot be decrypted (and poor error handling in the Add-on Builder). The most common scenario for this is that you copied the local/passwords.conf from one system (encrypted using the key on that system) to another system (which uses a different key). There has been one report of this behavior happening in a totally different app:  app1 uses the add-on builder setup. app2 used anything to create a passwords.conf but it was copied from another system so it wouldn't work there. The invalid passwords.conf in app2 prevents the app1 add-on builder from working.  Solution: go through and clear out any local passwords.conf. You can always move the files away and move then back to figure out which one is broken. Because that passwords.conf was never valid, it shouldn't cause any system impact to do so.  Enhancement for the Add-on Builder Team: replace this line of code with a try: e ... View more