The Common Name of the leaf certificate presented

@Miguel Angel Zavala López

Welcome to the Microsoft Q&A forum.

Based on the documentation here can you please check the following.

Cause: (For V2) This occurs when you have selected HTTPS protocol in the backend setting, and neither the Custom Probe’s nor Backend Setting’s hostname (in that order) matches the Common Name (CN) of the backend server’s certificate.
(For V1) The FQDN of the backend pool target doesn’t match the Common Name (CN) of the backend server’s certificate.

Solution: The hostname information is critical for backend HTTPS connection since that value is used to set the Server Name Indication (SNI) during TLS handshake. You can fix this problem in the following ways based on your gateway’s configuration.

For V2,

• If you’re using a Default Probe – You can specify a hostname in the associated Backend setting of your application gateway. You can select “Override with specific hostname” or “Pick hostname from backend target” in the backend setting.
• If you’re using a Custom Probe – For Custom Probe, you can use the “host” field to specify the Common Name of the backend server certificate. Alternatively, if the Backend Setting is already configured with the same hostname, you can choose “Pick hostname from backend setting” in the probe settings.

If the issue still persists, can you please share a screenshot of your health probe config and backend settings. Thank you!

ChaitanyaNaykodi-MSFT, I cant see you comment, can you repet please.

@Miguel Angel Zavala López

I have re-posted the comment above. Can you please let me know if you are able to view it?