Upgrading software can be daunting, and WHMCS manual upgrades are no exception.
This guide equips you with the knowledge to tackle three common errors and emerge victorious.

1. Allowed memory size exhausted |Resolved

The error message you’re encountering indicates that the PHP script has exhausted the memory limit allocated to it. This can happen when a script tries to allocate more memory than the limit set in the PHP configuration.

Fixing Error:allowed memory size of 33554432 bytes exhausted (tried to allocate 8192 bytes) in /path/to/whmcs/vendor/whmcs/whmcs-foundation/lib/Installer/Update/Updater.php on line 0 in WHMCS.

One solution is to increase PHP’s memory limit. You can do this by editing the php.ini file or adding a directive to increase the memory limit in your PHP script.

memory_limit = 128M

Or you can change it by,

Go to Select PHP Version-> Options, and change the memory_limit to 128M.

2. ionCube Loader extension | Resolved

The error message you’re encountering indicates that your PHP script requires the ionCube Loader extension to be installed and enabled. IonCube Loader is a PHP extension used to decode files encoded with the ionCube PHP Encoder.

Fixing Error: Script error: the inCube Loader for PHP needs to be installed.

To resolve this issue, follow these steps to install and enable the ionCube Loader extension:

  1. Download the ionCube Loader: Visit the ionCube Loader download page at get-loader.ioncube.com. Choose the appropriate version of ionCube Loader for your PHP version and operating system.
  2. Extract the Files: Extract the downloaded ionCube Loader files to a directory on your server.
  3. Enable ionCube Loader: Depending on your server setup, you may need to enable ionCube Loader in your PHP configuration.
  • Go to Select PHP Version-> Extension.
  • Enable the ioncube_loader

4. Restart Web Server: After enabling ionCube Loader, restart your web server to apply the changes

3. 503 Service Unavailable Error | Resolved

This indicates that the server is currently unable to handle the request due to temporary issues such as maintenance, downtime, or capacity problems.

Fixing Error: The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later. Additionally, a 503 Service Unavailable error was encountered.

To resolve this issue, check the session.save_path in both MultiPHP INI Editor and Select PHP Version.

  • This might be using a different session path.
  • If MultiPHP Manager uses the PHP version of Easy Apache, select the PHP version using the PHP version of Cloud Linux.
  • Check these paths and verify which is the correct PHP path your WHMCS is using.
  • If it is different, correct it in the MultiPHP INI Editor (as shown below) and reload the page.

If the issue persists or if you suspect that there might be an underlying problem with the server, contact your hosting provider’s support team for assistance.


If you face any problems with these issues or anything else during your WHMCS update, you can hire our experts for help or contact us by opening a support ticket to get a custom quotation. We’re here to assist you.

Ashily Shaji

Ashily Shaji

Ashily, a dedicated content writer at Ucartz, consistently applies her best efforts to her writing. Beyond her writing pursuits, she has a passion for travelling.