Sometimes, particularly after upgrading your WordPress website, you may encounter a WordPress error like the one shown below. This may happen for a number of reasons
Incompatible Plugin Breaking a WordPress Website

Understanding the Issue

The bulk of the code in WordPress websites is written in a language called PHP. The code interacts with a database to produce web pages that are displayed within your browser window.
PHP is installed on a webserver and is available in multiple versions, currently up to version 8. There was no PHP version 6. Typically you may see version 5.4, 5.5, 5.6, 7.0, 7.1, 7.2, 7.3, 7.4 & 8.0.
PHP versions 5.x are no longer supported by WordPress and WordPress plugins are usually written for version 7 and upwards. Similarly legacy plugins written for PHP 5.x may not work with systems designed for version. If you server is running PHP version 5.6 or below you may have issues with newer versions of WordPress. Similarly if you server is running PHP 7.x or above, you may find that old legacy plugins or themes break your website.
In an ideal world you should keep PHP, WordPress, your theme and all plugins updated to the latest versions.
In some instances, an incompatibility may cause a component to break. In the example above we have deliberately broken a plugin and are receiving an error message. This error message may also come by email.
PHP is installed on a webserver and is available in multiple versions, currently up to version 8. There was no PHP version 6. Typically you may see version 5.4, 5.5, 5.6, 7.0, 7.1, 7.2, 7.3, 7.4 & 8.0.
PHP versions 5.x are no longer supported by WordPress and WordPress plugins are usually written for version 7 and upwards. Similarly legacy plugins written for PHP 5.x may not work with systems designed for version. If you server is running PHP version 5.6 or below you may have issues with newer versions of WordPress. Similarly if you server is running PHP 7.x or above, you may find that old legacy plugins or themes break your website.
In an ideal world you should keep PHP, WordPress, your theme and all plugins updated to the latest versions.
In some instances, an incompatibility may cause a component to break. In the example above we have deliberately broken a plugin and are receiving an error message. This error message may also come by email.
Identify the problem from the error message

In this case, we can see that the error is within the plugin "visit-notifications", specifically in the file located at /home/wpsandbo/public_html/wp-content/plugins/visit-notifications/visit-notification.php
We will need to disable this plugin manually.
We will need to disable this plugin manually.
Login to your Webhosting account
You will need to access your file manager to do this. How you do this will depend on your webhost. In this examples we use cPanel, but the concept is the same across all platforms.
Disable the plugin

visit-notification
to visit-notifications.bak
This will disable the plugin. You will now be able to access and log into your website.
Article published 22nd June 2022
Last modified 02nd November 2023