Microsoft Explorer Login Does Not Work - login.microsoftonline.com - Opener tab must be in the same window as the tab being created

[influential-eliot]

Before submitting a bug report

• I updated to the latest version of Multi-Account Container and tested if I can reproduce the issue
• I searched for existing reports to see if it hasn't already been reported

Step to reproduce

1. I opened https://developer.microsoft.com/en-us/graph/graph-explorer
2. I tapped the login button
3. It opens the login pop-up
4. I go through the login flow
5. It hangs on the submission of the final stage of the flow and does not log in

Occurs on all tenancies ... separate tenancy - separate multiple account container.

Actual behavior

When I try to log in to the Graph Explorer in any given container (which already has a valid login.microsoftonline.com cookie) the login pops up (like any other Microsoft site) and then hangs at the last submission of credentials. It never actually logs me in.

Expected behavior

It should authenticate the final authentication, then pass the user back to the main window (MAC tab) to login.

Additional informations

OS - Windows 11 (latest)
MAC Version - 8.1.3
FF Version - Nightly 123.0a1 (2024-01-21) (64-bit)

This has been occurring for many months now.

This works just fine in EDGE in private mode.

It is fine for other apps in their suite, it is just the Graph API. They have somehow found a way (it would seem) to break out of the container with the login for this site specifically.

Looking at the Debugging Dev Tools for MAC I can see that the error in the Console is:

Uncaught (in promise) Error: Opener tab must be in the same window as the tab being created

Provide a copy of Troubleshooting Information page (optional)

No response