Troubleshoot and resolve InvalidArgumentException: Query string must not include a URI fragment errors.
Troubleshoot and resolve Down for Maintenance errors.
Troubleshoot and resolve duplicate system themes appearing in the System Theme menu.
Troubleshoot and resolve empty pages while using WHMCS.
Troubleshoot and resolve main(): Failed opening required '/path/to/whmcs/..filename.php' errors.
Troubleshoot and resolve The file cannot be decoded errors.
Troubleshoot and resolve File Not Found errors.