How to Fix – Fatal error: Cannot redeclare _wp_post_revision_fields()

WordPressI just encountered the following WordPress upgrade error when moving to 3.6 (though you may be experiencing it with WordPress 3.7 or newer):
Fatal error: Cannot redeclare _wp_post_revision_fields() in /home/xxxx/public_html/xxxx/wp-includes/revision.php on line 25

Pesky, huh? Easily fixed though. Download the latest copy of WordPress, then connect to your site via FTP. Rename wp-includes (or delete it) and upload a new copy from your newly downloaded version.

All should now be well!

It may have been related to my server load at the time causing a timeout.

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  • Ronda

    I am having the same problem, I am now uploading the new version of WP. Question does it matter what I rename the wp-includes folder? Will that effect the function of my site?

    • Mike

      Hi Ronda,

      No — it does not matter. You are renaming it so that it becomes inactive (basically, a backup). You then upload a new copy of it (which still has the name “wp-includes”).

      Hope that makes sense! :)