WordPress functionality is extended through the use of plugins. A plugin is simply a program that “hooks” into the WordPress application programming interface (API) that allows developers to write code that changes the way WordPress behaves or interacts with other resources. There are literally over 16,000 plugins available on WordPress.org. This does not include plugins that are for sale only on an author’s website. Most plugins on WordPress.org are free or offer a free limited functionality version with a fully featured “Pro” version at nominal cost.
Some plugins produce HTML or JavaScript source code that is inserted into your site’s pages at the time they are rendered by WordPress. Sometimes this source code conflicts with existing functionality producing undesirable effects or, in a worst case, a broken website. Troubleshooting plugin issues can be a very tedious and time consuming process. When a conflict is discovered, most people will notify the plugin developer(s) and most responsible developer(s) will do their best to fix the issue and make sure that their plugin plays nicely with other plugins.
Another issue that appears from time to time is that the source code produced by a plugin does not pass W3C validation. I explained about W3C validation in How to Fix facebook Related W3C Validation Errors, so I won’t repeat that content here. But let it suffice to say that many SEO consultants believe that failing W3C validation negatively impacts search engine rankings. With the fierce competition we all face, we need to do everything possible to achieve the highest ranking we can muster. And whether errors impact search engine rankings or not, if the code a plugin produces can’t pass validation, it means it is not written to a standard that improves interoperability across a wide array of browsers. Some plugin developers simply don’t care about validation at all. They’ve told me that the functionality they provide is far more important than writing good, validated code. This attitude is not the norm. Most plugin authors I’ve communicated with really do their best to ensure their plugin is compatible and well written, and they are very responsive to the needs of their customer base.
In order to help you avoid the pull my hair out, throw the keyboard across the room type of troubleshooting sessions that searching for a misbehaving plugin can produce, this page documents plugins that either I or another developer I trust have encountered. If there is a known workaround, it’s documented. If it fails W3C validation, it is also documented. We are always at risk when we use plugins on our sites, but the fact is, we need plugins to help us accomplish our vision. Using the plugins on this list increases your risk of something going wrong. But ultimately, it’s your choice.
If you’ve encountered a plugin that either breaks other plugins or fails W3C validation, please use this Plugin Report Form to send me the details.
| Plugin | Bad Behavior (all versions) | Passes W3C Validation? | Yes |
| Author | error, markjaquith, skeltoac | ||
| Known Conflicts | Bad behavior causes many conflicts with other plugins, especially any having to do with eCommerce and payment gateways such as PayPal or Authorize.net. A common complaint is that Bad Behavior blocks transactions from getting recorded as complete in the eCommerce database | ||
| Known Workarounds | Bad Behavior includes whitelist functionality that will permit payment gateway urls to pass through it’s filtering. | ||
| Author Comments | Not available | ||
| WordPress.org Forum Post | http://wordpress.org/tags/bad-behavior?forum_id=10 | ||
| Plugin | JetPack—After the Deadline Ver. 1.1.3 | Passes W3C Validation? | Yes |
| Author | Automattic | ||
| Known Conflicts | After the Deadline conflicts with Simple URLs plugin from Studio Press | ||
| Known Workarounds | Automattic has identified a bug in After the Deadline and will provide a fix in the next release of JetPack. In the meantime, if you want to use the After the Deadline feature:
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| Author Comments | None | ||
| WordPress.org Forum Post | http://en.forums.wordpress.com/topic/jetpack-conflict-with-simple-urls-plugin | ||
| Plugin | JetPack—Sharedaddy Ver. 1.1.3 | Passes W3C Validation? | No |
| Author | Automattic | ||
| Known Conflicts | Plugin fails W3C validation if Twitter smartbutton is turned on | ||
| Known Workarounds | Don’t turn on the Twitter smartbutton | ||
| Author Comments | None | ||
| WordPress.org Forum Post | N/A | ||
| Plugin | Simple facebook Connect (SFC) Ver. 1.1 | Passes W3C Validation? | No |
| Author | Otto | ||
| Known Conflicts | Allow PHP in pages and posts by Hit Reach—when SFC is activated, PHP code inserted in posts or pages does not execute. No error messages are produced. | ||
| Known Workarounds | None | ||
| Author Comments |
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| WordPress.org Forum Post | http://wordpress.org/support/topic/plugin-simple-facebook-connect-latest-version-breaks-other-plugin | ||
| Plugin | WP-eMember (all versions) | Passes W3C Validation? | No |
| Author | Rahul Amin—Tips and Tricks HQ | ||
| Known Conflicts | Plugin does not pass W3C validation and produces many errors. | ||
| Known Workarounds | I use this plugin myself, and have modified the source to correct the validation errors. Unfortunately, I am stuck with version 7.09 because in later versions, the author changed the method in which his code is inserted into pages. | ||
| Author Comments | Author states the code that produces the validation errors should rightly be loaded into the WordPress footer, but that he will not do that because of badly written themes that do not call the wp_footer() action call and he wants his plugin to be compatible with as many sites as possible, badly written theme or not. | ||
| WordPress.org Forum Post | This author does not market his plugins on WordPress.org. He offers a members only forum on his website where this issue is documented. | ||
| Plugin | WP-eStore (all versions) | Passes W3C Validation? | No |
| Author | Rahul Amin—Tips and Tricks HQ | ||
| Known Conflicts | Plugin does not pass W3C validation and produces many errors. | ||
| Known Workarounds | This plugin produces numerous unescaped ampersand errors. The author has stated that he will not fix them because they are unimportant. If you want to pass W3C validation with this plugin, you must edit three files: eStore_includes.php, wp_eStore1.php, and eStore_misc_functions.php | ||
| Author Comments | None | ||
| WordPress.org Forum Post | This author does not market his plugins on WordPress.org. He offers a members only forum on his website where this issue is documented. | ||
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