Hi @KennethSong
There are several reasons for certificate verification to fail.
Invalid certificate being one of them.
- Have you set the correct trusted root CA certificate?
- Is the server hostname same as the certificate CN in subject name \ subject alternative name ?
You should check what the verification flags are to determine the reasons, by calling mbedtls_ssl_get_verify_result()
P.S. I also tried to enable the error log by adding MBEDTLS_DEBUG_C and set Debug_Level to 4, but i can not get the log through serial. Do anyone know why?
Have you set correct debug function in mbedtls_ssl_conf_dbg() ?
regards,
Mbed TLS Team member
Ron