SAML (AzureAD) Certificate used in the document does not match any registered certificate

Sonarqube Version: 9.2 (build 49834)

I want to setup SAML authentication using AzureAD.
I did the initial setup based on your documentaion: Delegating Authentication | SonarQube Docs
When i hit a redirect issue, this was addressed in SAML error with nginx reverse proxy

Now i am facing the error Certificate used in the document does not match any registered certificate

The SAML authentication is already passed by the AzureAD but sonarqube cannot validate the SAML Response.

I already registered the AzureAD publickey (X509 CER as string) of my SAML configuration in the sonarqube Provider certificate.
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Question:

  • What can be the reason for this error?
  • I do register the certificate string as a regular CER file. Is this correct or do i need to use a different format?
  • Do you have a documentation for howto setup AzureAD as saml provider?