Troubleshoot and resolve issues when attempting to use an admin invitation link.
Troubleshoot and resolve main(): Failed opening required '/path/to/whmcs/..filename.php' errors.
Troubleshoot and resolve The following recipients failed errors.
Troubleshoot and resolve A fatal error occurred while fetching the update errors.
Troubleshoot and resolve Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 20480 bytes) errors.
Troubleshoot and resolve issues that affect multiple features immediately after an update.
Troubleshoot and resolve Field xxx doesn't have a default value errors.