Troubleshooting Licence Connection Error

A connection error on the admin login page occurs when your server has been unable to connect to our licensing server for several days:

This is commonly caused by a CURL or DNS resolution problem, these are essential items in the use of WHMCS and is something your server admin will need to investigate and correct:

CURL
CURL is an extremely important part of WHMCS and is needed for a number of the operations performed such as server connections etc.

DNS
DNS is a vital part of internet functionality in order to be able to resolve hostnames of servers, domain name lookups, and licensing. Ensure your DNS resolve whmcs.com to the correct IP address.

To test the connection between your server and the WHMCS licence server, a built-in test tool is available on the admin area login page:

/admin/login.php?conntest=1
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For example, if your admin area is located at http://example.com/admin/login.php, you'd visit http://example.com/admin/login.php?conntest=1.

A successful test result looks like:

    Testing Connection to 'https://a.licensing.whmcs.com/1.0/test'...
    URL resolves to 208.74.120.154 ...
    Response Code: 200
    Connection Successful!
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If you see any errors, it will be necessary to work with your server admin/hosting provider to resolve the cURL connectivity issue. Showing the test results should assist in their troubleshooting.

Caveat for Shared and Reseller Hosted Customers

Some hosting providers may operate very restrictive environments, which results in a No Connection error despite the aforementioned test returning a successful result.

In this situation, changing the PHP version to 7 can resolve the error. For more information, see the  HostGator documentation.