When you install WHMCS on a server, make sure to watch for errors both during and after the installation process.
You might see license-related errors if you cannot connect to the WHMCS license server or there is a misconfiguration in your system.
Troubleshoot and resolve Curl Error: Couldn't connect to host (7) errors.
Troubleshoot and resolve Curl Error - Couldn't resolve host (6) errors.
Troubleshoot and resolve Your license key is invalid errors in the API.
Troubleshoot and resolve License Invalid errors.
Troubleshoot and resolve Invalid License errors on HostGator servers.