Note
Access to this page requires authorization. You can try signing in or changing directories.
Access to this page requires authorization. You can try changing directories.
Symptoms
When you try to access a SharePoint Online site, you receive the following error message:
Bad Request - Header Field Too Long
HTTP Error 400. A request header field is too long.
This error indicates that the size of the HTTP request header that was sent from the browser is too large.
Cause
This issue might occur if you try to access a SharePoint Online site many times in a short period before you complete the sign-in. This adds too many cookies to the request. This, in turn, causes the HTTP request header to become too large.
Resolution
To resolve this issue, delete cookies in Microsoft Edge. If you use third-party browsers, check their support sites for instructions to delete cookies.