General errors can occur in many places throughout WHMCS, and can be due to many different problems. However, fixing them is often simple.
Each addon module has specific errors that you might encounter.
Authentication issues may include inability to log in, unexpected logouts, or errors while using other authentication methods.
We support many different ways to customize your WHMCS installation, all of which have their own troubleshooting needs.
When you sell domains, issues with domain availability checks, registration, or renewals can cause serious problems.
When you install WHMCS on a server, make sure to watch for errors both during and after the installation process.
Issues with invoices and invoice generation can be due to many causes, some of which may not be obvious at first.