When I used openssl APIs to validate server certificate (self signed), I got following error :
error 19 at 1 depth lookup:self signed certificate in certificate chain
As per openssl documentation, this error (19) is
"X509_V_ERR_SELF_SIGNED_CERT_IN_CHAIN: self signed certificate in certificate chain - the certificate chain could be built up using the untrusted certificates but the root could not be found locally."
Why this error occurs ? Any problems with my server certificate ?
You have a certificate which is self-signed, so it's non-trusted by default, that's why OpenSSL complains. This warning is actually a good thing, because this scenario might also rise due to a man-in-the-middle attack.
To solve this, you'll need to install it as a trusted server. If it's signed by a non-trusted CA, you'll have to install that CA's certificate as well.
Have a look at this link about installing self-signed certificates.