Issue when opening Planner via browser

Question

Hello everyone,

we are currently experiencing an issue when opening Planner via browser: every time, the sign-in screen appears and we are asked to sign in with our Microsoft account. This happens even though we open it directly via https://planner.cloud.microsoft. 

After we sign in, close the browser, and open Planner again, we are prompted with the sign-in screen once more.

While checking the cookies, I've noticed that no authentication information was created when signing in via direct url.

  

Using https://m365.cloud.microsoft/apps/ and open Planner from the Apps section, it creates authentication information in Edge / in the cookies.

 

Has anyone else experienced something similar?

Is this a known / general problem?

Answer 1

Hello,

We had the same issue. As a workaround, we were able to start the session via office.com and obtain a session cookie that remained active even after closing the browser.

However, as of today (2026-02-26), we are no longer able to reproduce the issue.

Answer 2

I have the same issue. Is there a workaround? Eventually I got this error: