Symptom
Under Onpage > Analysis management > example.com the message Error start URL is displayed
when the page is called, a 301 (redirect) HTTP status code is returned
with Google DevTools you can see that the response header does not have a location header Location::
Cause
The 301 status is returned, but a location header is not available.
Solution
Make sure that the location header is available if a redirection is set up.
or
Log in to suite.xovi.net
navigate to Onpage > Analysis management > example.tld
set the crawl scope to all subdomains and restart the onpage analysis by clicking on START ANALYSIS WITH CHANGED SETTINGS