Hello,
Thank you for reaching out to the Microsoft Community and I'll be glad to assist you today.
Yes, a few users have reported seeing the "500 Internal Server Error" when trying to open their inbox on Outlook.com within the last two hours. It looks like it might be a temporary issue on Microsoft’s end.
I recommend waiting a few hours and then trying again to see if the problem is resolved.
In the meantime, some users have been able to access their emails by signing in using an Incognito or private browsing window.
Here's the recent discussion thread for your reference:
https://support.microsoft.com/help/dd92bebc-816...
The thread is in Spanish. We recommend using a translator if required.
Let me know if you still need more help.
Best regards,
Gunasekar N