Apache proxy server (with SSL) - troubleshooting

When SSL connection to server fails, first retry the connection using Chrome. Chrome give more information on the problem.
Below is list of Chrome errors and possible ways to troubleshoot them.

Error 102 (net::ERR_CONNECTION_REFUSED): The server refused the connection. 

Possible problem: Apache is down.
How to check:

• Stop Apache
• Check that its ports (usually 80 and 443) are not used 
• Start Apache
• See in its console if there is any error message

Error 111 (net::ERR_TUNNEL_CONNECTION_FAILED): Unknown error

Possible problem: Apache got into internal problem.
How to check: 

• Restart Apache
• Check if this solved the probelm
•   

Not Found (404) - The requested URL /XYZ was not found on this server.

Possible problem: The apache that you think that start is not the actual one OR the configuration files that you think are read by apache are not the expected one.
How to check:

• Stop Apache
• Delete configuration files (each time only one file)
• Start Apache and see if it print error on missing configuration file.

Possible problem #2: Apache proxy settings have some conflicts.
How to check:

• Stop apache
• Comment out any proxy settings in httpd.conf that you are not familiar and are there by default.
• Start apache