Can't connect to TYPO3 slack

Tim reported an issue

I cannot connect my TYPO3 account to slack. After login I'll get redirected to login page again.

Reported URL:https://my.typo3.org/index.php?id=15&no_cache=1

User Agent:Mozilla/5.0 (Windows NT 6.1; WOW64; Trident/7.0; rv:11.0) like Gecko