Why Do Plugins Conflict on WordPress?

How Plugins Interact with WordPress

Plugins are add-ons to the main WordPress software. They can do two things: make edits to information going into the database or to a Web page as it is produced, and perform actions that are in addition to WordPress' actions. For example, when you write a new post, a plugin could send out an email notification -- an action that adds to what WordPress itself does. The plugin could not, however, prevent WordPress from saving the post in the first place, because that would modify something WordPress itself already does. A plugin can, however, modify some of the information that WordPress saves into the database.

Plugins perform their actions in order, one after the other, after the main WordPress software performs its actions. The plugins' behaviors are not regulated by a central authority, so the order they act in is uncontrolled. Conflicts can arise when one plugin modifies a piece of output or performs added actions in one way, and then a plugin that acts later in the queue does so in a contradictory way.

WordPress plugins are not centrally regulated, so some WordPress functions are served by numerous choices of plugins that do different things. For example, many developers have created WordPress plugins to perform actions related to search-engine optimization. Some are more thorough than others, but most will also do some common optimization-related tasks such as rewriting page titles or adding keyword meta tags. If you add a couple of plugins that include some of the same tasks but that perform them in different ways, conflicts can arise.

It may be difficult to troubleshoot and identify where plugins are conflicting. For this reason, you should try to avoid overlapping plugins as much as possible. When you are looking for a plugin to perform a specific task, investigate your options thoroughly, test them with your WordPress installation, and choose the one that works best for you. Deactivate the ones that didn't make the cut.