During the processing of petitions it is possible for the responses returned by Registry to be a series that only includes HTTP response code 302, that is a redirect. The Firefox browser has a default limit to the number of 302 redirects that it will follow before displaying an error to the user. The default is 20. Note that the series of redirects need not include a loop for Firefox to stop processing and display the error page.
With an enrollment plugin(s) configured it is possible for Registry to return a series of more than 20 redirects and for the user to see the Firefox error page even though the enrollment petition flow and the process would otherwise be valid.
The Firefox setting, accessible from the 'about:config' page is