SOLVED

Getting 'Request too long' when hitting the MDI portal

Occasional Contributor

Over the last week, more and more of our support teams have been seeing "Bad Request - Request Too Long.  HTTP Error 400: The size of the request headers is too long" messages when hitting https://ourATP.atp.azure.com/timeline 

Anyone else seeing this ?

Clearing cache, inprivate, different browsers, different users....none seem to fix it. Then all of a sudden it will just work.  I am assuming backend issues...but curious

4 Replies
best response confirmed by StuartH . (Occasional Contributor)
Solution
Known issue, engineering are working on a hotfix.
Once fixed, you should delete the local cookies, try again and it should work.
You can track status here:
https://health.atp.azure.com/incidents/tmcrvr4pkbbd

Thanks for the super quick acknowledgement. Wish all MS product teams supported their products in such an open, fast and consistent way. Thanks Eli

Another potential cause for this behavior is having a large amount of AAD group memberships resulting in a very long access token, as discovered by @Per Stromberg . So if there is no service outage and all browser caches have been cleared and the issue still persists, that is a good area to turn your attention to next.

My workaround is to launch it using an InPrivate window.