WordPress Yet Another Related Posts Plugin Admin Page Blank, Call to undefined function yarpp_reinforce()

While upgrading the WordPress plugins today for a WordPress site I manage today I ran into an issue with the YARPP (Yet Another Related Posts Plugin). This WP plugin provides links to like articles on each of the posts of the site. You can cross reference various variables such as titles, content, tags, and categories. After upgrading the YARPP plugin this afternoon I noticed issues during testing when the YARPP configuration page would not display via the WordPress admin. Below is information on the error that was located in the PHP error logs, what was initially attempted to resolve the issue, and what did resolve the issue with the YARPP settings page.

Yet Another Related Posts Plugin Settings Page Blank:

The issue after upgrading from Yet Another Related Posts Plugin version 3.1.9 to Yet Another Related Posts Plugin version 3.2.1 was when attempting to bring up the YARPP settings page in the WordPress admin site the page was blank. After looking into the problem the below error message was located in the PHP error logs on the server.

Yet Another Related Posts Plugin PHP Fatal Error:

[22-Feb-2011 23:26:47] PHP Fatal error: Call to undefined function yarpp_reinforce() in /var/www/path/to/wordpress/wp-content/plugins/yet-another-related-posts-plugin/options.php on line 73

Initial Attempts To Resolve The Blank YARPP Settings Page:

I typically do not follow the proper upgrade path for WordPress plugins which includes deactivating the plugin, backup the plugin directory on the server, remove the plugin directory from the “wp-content/plugins” directory, upload the new plugin files to the server via FTP, and activate the plugin. What I typically do is simply overwrite the files on the server via FTP and then test to make sure all went well with the plugin upgrade. When the YARPP upate failed I figured the issue would likely be resolved by deactivating the plugin and then activating YARPP again however the same issue existed.

How The Blank YARPP Settings Page After YARPP Plugin Update Issue Was Resolved:

Since I was unsuccessful in my method of upgrading the Yet Another Related Posts Plugin I decided to try the correct method this time. I first deactivated the YARPP plugin and backed up the “wp-content/plugins/yet-another-related-posts-plugin” directory to another location on the server. Next I deleted the yet-another-related-posts-plugin directory completely from “wp-content/plugins”. After all of the YARPP files were deleted I uploaded the files, which had been extracted from the yet-another-related-posts-plugin.3.2.1.zip file downloaded from the WordPress site, to the “wp-content/plugins” directory. Last but not least I activated the Yet Another Related Posts Plugin and visited the YARPP Settings page to verify things were working and sure enough this time the YARPP Settings page was displaying in the WordPress admin.

Another lesson in following directions… :)