Azure Web Application Firewall Certificate Error

Darren Muizelaar 0

Hi,

I have apache2 running on one of my virtual machines. It has multiple SSL certificates, multiple domains, if i connect directly there are no issues. If i use the WAF i see a 502 error with the WAF displaying the following message in the backend health.

Backend server certificate is not whitelisted with Application Gateway. Make sure that the certificate uploaded to Application Gateway matches with the certificate configured in your backend server. To learn more visit - https://aka.ms/authcertificatemismatch.

I have never had this issue before and the WAF looks like it is configured correctly but in the last few weeks have seen this error. Can anyone help?

Darren Muizelaar 0 Reputation points

2024-05-18T17:52:33.6833333+00:00

I have read the described document and its not telling me anything i already know.

https://aka.ms/authcertificatemismatch
KapilAnanth-MSFT 46,776 Reputation points Microsoft Employee

2024-05-20T07:53:57.0366667+00:00
@Darren Muizelaar ,

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

I understand that you are having a VM as a backend of Application Gateway and I see you are using a custom root certificate instead of "Use well known CA certificate".

If you are using a well known certificate,

I would suggest you enable the option "Use well known CA certificate".

If you are using a self-signed certificate,

Make sure the Root certificate path is correctly configured, i.e., properly bundled.

You can check this in Backend health

Please share your backend status with "Backend server certificate visualization"

May I know how did you acquire the root certificate and the leaf certificate?

Can you share the certificate path of the Root certificate?

Like displayed in a browser

Cheers,

Kapil

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