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Jan Liikamaa's avatar
Jan Liikamaa
Copper Contributor
Oct 28, 2025
Solved

Certificate authentication with SID not working

When trying to login to Windows (against AD) using a certificate with the SID extension present in the certificate, it will not work if the SAN UPN is missing in the certificate. The error message "Y...
  • hasanemresatilmis's avatar
    Oct 30, 2025

    Yes, this behavior is by design. Windows certificate-based logon requires the Subject Alternative Name (SAN) extension with a valid User Principal Name (UPN) for proper mapping to the AD user account even if the SID extension is present.

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