This article will explain how to troubleshoot WHMCS allowing you to resolve many of the most common error messages that you may experience while using WHMCS.
The developers of WHMCS sometimes identify bugs between releases. They typically release individual patches that are published outside the update structure which you can apply to your WHMCS install if you are experiencing any symptoms. For information on any known bugs inside WHMCS, please review their HotFixes page in helping you resolve any issues you are going through.
Module Command Errors are errors you may experience that are returned from the module and not WHMCS. These provisioning modules (cPanel, Plesk, etc.) come from your server, for registrar modules (eNom, Tucows, etc.) they come from your domain registrar.
Therefore to discover the cause of such errors refers to your server/registrar’s documentation or support team. We have collected some of the most most common errors and their causes, refer to the appropriate page in the following sections. Once you review the error and make the necessary corrections to your server use the Module Command buttons under the client’s Products/Services or Domains to review the changes you’ve done.
Sometimes WHMCS does not recognise all errors that happen inside the software. These errors result in an Unknown Error message displayed in WHMCS. During these situations, the System Module Debug Log can be used to obtain the full error message from the module. The system module debug log, Utilities > Logs > Module Log, contains the error message that the server/registrar documentation and support team will need to help in resolving the error in WHMCS.
If you experience a blank page in the WHMCS system ensure display_errors is turned on inside the server’s PHP configuration and also enabled in the Setup > General Settings > Other tab > Display Errors option.
After you have verified display errors is on, take the same steps as before to reproduce the blank page. This time, on the blank page you should see an output error message on the page. WHMCS has compiled several of the most frequent errors produced inside the CMS and they can be reviewed by visiting the page Common Troubleshooting Tips-Server Errors.
Sometimes you may experience a payment not being registered in WHMCS. If you experience this in your CMS, the first thing to check is that the callback settings on the website of your payment gateway are configured to communicate with WHMCS. As a general rule of thumb, all callback commands should be sent to the correct file in the /modules/gateways/callback directory. All specific instructions for setting up individual gateways can be found on the WHMCS Payment Gateways informational page.
After reviewing your gateway configuration and it is correct, navigate to Billing > Gateway Log and review the debug information created at the time of payment. The report should display an error message or code that can be used with your payment gateway’s documentation or by their support team to assist you in resolving the error.
If there is no log created at all in WHMCS and you have a merchant gateway setup correctly, it is suggested that the customer has no credit card details on file. This error typically means that your gateway is unable to communicate with the callback file. Your server may be blocking the action by using a firewall or mod_security. If you are experiencing this issue, communicate with your payment gateway and your hosting company to resolve the error messages.