← cd ~/errors
// entra id sign-in error · app registration and tokens
AADSTS700027
Client assertion signature failed
What it means
The client assertion failed signature validation.
How to fix it
The certificate used to sign doesn't match one uploaded to the app registration, or it has expired.
How to investigate
- Compare what the app sends (client ID, redirect URI, scopes, tenant) with the app registration.
- Decode the token or request: the JWT and SAML decoders on this site show exactly what was sent.
- Check the app's credentials (secrets and certificates) and whether the service principal exists and is enabled in this tenant.
- Search the sign-in logs for the request ID or correlation ID from the troubleshooting details on the error page.
Guides on this site
Tools that help
Error names and meanings follow Microsoft's error code reference. The fixes are this site's guidance.