How can recognize an expired certificate on MQTT connection

[lucilla2002]

In a MQTT connection how can I recognize the use of an expired certificate from

esp_mqtt_connect_return_code_t and esp_mqtt_error_type_t values?

I haven't expired certificates so I don't know how I can detect this situation

[ESP_YJM]

There is no API to get the reason code you want. But you can try add some log in esp_mbedtls_verify_certificate in esp_tls_mbedtls.c to print flags value. If the flags value is MBEDTLS_X509_BADCERT_EXPIRE, it means the server CA certificate is expired.