Troubleshooting a blank page
When changes are done to your Joomla! website, sometimes it comes up a totally white page. Since you are a website administrator, it’s you who is responsible for making Joomla! show up again. The information below will help you troubleshoot the blank page.
In fact, when you run across a blank page and analyze it, you can be surprised that there is barely nothing to troubleshoot since this page does not show anything, so staring at the screen (even with the developer or some other expert) is pointless. The problem of the blank page is explained by some server setting which hides this information for you and your website visitors.
In most cases the white page can appear if server that runs PHP failed in some way or something went wrong with the PHP-scripts you attempted to run with current server configuration. The reason can be detected by means of contacting the system administrator of your server and asking him to check the Apache error logs where errors of this type usually go to.
You also can try to resolve the problem of the blank page by making Joomla! to display the error. It’s quite easy and considered a basic administrative task for which fulfillment you should select Global Configuration, then go to Server tab and modify Error Report setting. For the errors to be displayed, you should choose the value either Maximum or Simple.
It’s best not to select the Development if you are not a web developer, and not to modify System Default if you don’t administrate your server yourself since it’s not under your control.