Joomla shows a white screen

A white / blank screen is the most annoying error you can have, because you cannot figure out the cause of the problem when there is no error message to be seen.

So first we need to make sure that the error can be seen. There are several ways to do this.

Enabling error reporting

If you have access to the administrator area of your website, go to System > General Settings and go to the "Server" tab.

There you will see the "Error Reporting" option. Set this option to "Maximum" and view the front end of your website to see the error message.

Enable error reporting via the configuration.php file

If the administrator area of the Web site also gives a white screen or you have no access due to other reasons, go to the configuration.php file of the Web site via FTP.

Find the line starting with public $error_reporting and change it to:

public $error_reporting = 'maximum';

Look at the frontend of your website to see the error message.

You found the problem and now?

Even if you don't fully understand the error message, you can probably see where the problem is now.

Fixing an extension error message

If you still have access to the administration screen of Joomla, you can disable the extension.

If you do not have access, you can disable the extension via FTP by changing the folder name (e.g. mod_openinghours to mod_openinghours-disabled).

Also, check for updates to the extension that probably already fixed the problem.

If it is not fixed, contact the extension developer.

Fix error message in Joomla

If the error is in Joomla itself, try overwriting all files with the original files.

In Joomla, get to this screen via System > Joomla > Update and check for updates. First click on check for updates and then you will see the screen below.

Even if you get to see that you have the latest version, try to reinstall the Joomla core files,

If you don't have access to the admin area then you need to overwrite the files via FTP.

Go to downloads.joomla.org and download the latest version. Copy and overwrite all the files (except the installation folder, you should not copy it again).