SSL_CTX_use_PrivateKey_file() failed

The error error:0906D06C:PEM routines:PEM_read_bio:no start line is because in both the cert.pem as well as key.pem, don't start off with -----BEGIN CERTIFICATE----- and -----BEGIN ENCRYPTED PRIVATE KEY-----.

If you open up your cert.pem and key.pem in a text editor and yank off whatever is there before the BEGIN markers, you should be good.

When you create a certificate and a key pair using Certificate Signing Request, you won't get this additional information.

I've solved this problem myself. I generated the key.pem using OpenSSL for Windows, when the CMD prompts me to type in the pass phrase, I just typed a Enter since I needn't a pass phrase, but the key.pem was invalid(neither BEGIN nor END markers). When I generate the private key in Linux, the terminal prompts I must type a pass phrase and I do. Then I remove the key pass phrase using this command:

openssl rsa -in key.pem -out newkey.pem

After that, I open the key.pem in a text editor, it starts off with -----BEGIN RSA PRIVATE KEY----- and end up with -----END RSA PRIVATE KEY-----. And SSL_CTX_use_PrivateKey_file() just works fine!

In my case the error was because the PEM file did not contain both a key and a certificate.

Make sure your file contains both sections:

-----BEGIN PRIVATE KEY----- jhajk838383jks.....
-----END PRIVATE KEY-----
-----BEGIN CERTIFICATE----- yoe55wjcxnshre.....
-----END CERTIFICATE KEY-----

I catenated .key and .crt files I already had in my Apache configuration to make a .pem file.

The 'no start line' error is certainly misleading as you can have a perfectly good "BEGIN" line in your PEM file and still get the error.