Error messages like 'Proxy error', 'invalid response', '404 error' or 'The page isn't redirecting properly' can often be caused by cookies on your web browser. To fix this, you will need to clear the cookies in this browser. Details of how to do this can be found below.
To delete all cookies and cache you need to go into your browser menu.
For further details, Exeter IT have provided the guide on clearing cache and cookies @ https://as.exeter.ac.uk/it/helpdesk/clearcache/
You don't necessarily have to clear you cookies and cache to fix the problem.