Just completed an upgrade and we are getting the error message - "There is no query runner registered" "Internal Server Error" after restarting Splunk.
Are you looking for what this error might mean? Is there a situation when this message means to take this action, like when upgrading to a particular release?
This sounds the same as THIS answers issue.
Check and verify that your indexes are enabled in new release.
Is this specific to some version? Is it a bug?