AADSTS50126

What it means

The username or password is wrong.

How to fix it

Some are normal user error. Many from one IP across many users suggests password spray.

How to investigate

1. Confirm which account the user actually signed in with. A personal account or the wrong tenant causes many of these.
2. Check the user object: enabled, licensed, in the right tenant, and with no recent password change or reset.
3. Look at the sign-in logs over a few days for a pattern, such as repeated failures from one IP address.
4. Search the sign-in logs for the request ID or correlation ID from the troubleshooting details on the error page.

Guides on this site

• Six KQL queries for Entra sign-in logs every admin should keep

Tools that help

• Sign-in log explainer
• KQL library
• Microsoft's error lookup for 50126 ↗