How to troubleshoot and resolve cURL error 28: Operation timed out errors.
If you have remained on a WHMCS version that is past its End of Life (EOL) date for multiple years, we recommend that you update WHMCS as soon as possible. Make sure that you meet the system requirements for each EOL version that you upgrade through to reach a modern, supported version.
You can check for updates to WHMCS from within the Admin Area.
Before you update your WHMCS installation, we recommend several preparatory steps.
You can set a maintenance message to display while you update WHMCS.
You can set a directory to use to stage files for updates.
You can configure the update channel to use for WHMCS updates.