How to update ioncube loader for WHMCS 7
If you are trying to install WHMCS 7 or WHMCS 7.1 on cPanel / WHM and encounter a white page when trying to view WHMCS in a browser, you probably need to update ioncube loader to the latest version for WHMCS to work correctly. You can view the Apache error logs look for any ioncube related errors like the one below.
PHP Fatal error: The file cannot be decoded by this version of the ionCube Loader. If you are the administrator of this site then please install the latest version of the ionCube Loader. in Unknown on line 0
As of December 17 2016, the latest version for PHP 5.6 is ioncube6 (experimental). You will want to make sure you have updated CPanel' / WHM to the latest version first.
To do this via WHM you can type in "update" in the WHM search bar, then click on "Update to latest version". Once that page loads simply click update now. The WHM update can take between 5 - 10 minutes to complete, it's ideal to do this update during low traffic hours as the update will increase server load while it's running.
To update WHM via command line you can simply ssh into the server and run:
Once you have confirmed that cPanel is up to date you need to run Easy Apache 3 or Easy Apache 4 depending on how up to date your system is. When you run Easy Apache you want to ensure that Ioncube loader is selected for PHP, if there are multiple versions of ionbube loader to choose from, select the newest version, then run tell Easy Apache to rebuild. Even if you already have Ioncube selected you will want to rebuild anyway.
Easy Apache 3
If you are using Easy Apache 4 you can login to WHM, search for "easy" in the WHM search box. Click on Easy Apache 4, then click on "customize" for your current profile
Click on "PHP Extensions" and search for "ioncube". Ensure that you have selected (click the blue toggle thingy) the latest version of ioncube loader for the version of PHP you are using. If you are using multiple versions of PHP just selected all the ioncubes.
Finally, click on the "Review" tab, and tell EA to rebuild the current profile. This should only take a few minutes to complete.
At this point you should be able to install and use WHMCS without any issues]