Hello, Mathias.
We are glad to have you at Microsoft’s Community.
As we understand from your post, you are unable to sign in to Microsoft Learn.
Please keep in mind that our Team provides support related to Microsoft Certifications profiles, and our access to Learn portal is limited.
In this case, we kindly suggest that you follow some basic troubleshooting steps before attempting to access your profile.
Make sure to use an up-to-date browser. (e.g., Edge)
Clear cache and cookies.
Make sure you check Preserve Favorites, website data and check both Temporary Internet Files and Cookies; then click Delete.
On the Delete Browsing History window, make sure to uncheck Preserve Favorites, website data and check both Temporary Internet Files and Cookies; then click Delete.
Allow all third - party cookies through the browser settings.
Please make sure that you have the latest version of the Edge browser or Internet explorer.
In case the issue persists, you can reach out Microsoft Learn thru this troubleshooting guide or provide specific feedback to Microsoft Learn by reporting an issue.
We hope this information helps you.
Please let us know if there is something else we can do for you. In case we do not receive a response, the thread will be closed and locked after one business day.
Wishing you a beautiful day,