global administrator error message

Question

I am a global administrator on our Microsoft 365. I can't get into the admin portal. I get this error message "Bad Request - Request Too Long HTTP Error 400. The size of the request headers is too long." How do I fix this?

Answer 1

Hi Nancy,

We're glad to receive your feedback.

From your reply, you can sign in admin center via Firefox but not Edge, the issue could be relate to the browser. Therefore, you first can clear the cache about browser to check if it is workable. Besides, since there are two global administrators in the organization, you can refer to my previous reply to contact another to re-assign your admin role to check the result.

Looking forward to your update and we'll always be here for you.

Regards,

Joey

Answer 2

I'm using the newest version of Microsoft Edge and targeting this URL  https://admin.microsoft.com/AdminPortal/Home

Answer 3

Hi Nancy,

Welcome to post in the community.

From your description, to exclude the issue associated to the browser, you can use In-Private Mode in the browser or use other browsers to sign in to check if it is workable. Besides, we'd like to know if there are other global administrators in the organization. If yes, please let them to sign in Microsoft 365 admin center to re-assign the role to you. Besides, it is recommended that don't assign too much roles to you.

If you have anything unclear, please feel free to let us know.

Regards,

Joey

Answer 4

Couple quick questions.

What browser are you using and what URL are you targeting?