WP_DEBUG_LOG: Logging Error Messages for a Live WordPress Site

Who doesn’t know the situation? Something is going wrong with WordPress. With the configuration, a plugin or a theme and you ask the support community asks for error messages.

To receive those messages in WordPress, you can activate WP_DEBUG. Setting it to the value TRUE causes WordPress (or better PHP) to document all errors in the browser.

Doing so on a productive website might look – hm – not good. What to do?

Logging error messages

With the following lines, added to the wp-config.php, you can log all the errors in a file instead of getting it in the browser:


  • You are in Debug-Mode.
  • No errors will be showed in the browser.
  • All error messages will be documented in /wp-content/debug.log.


Better safe than sorry. By default WP_DEBUG_LOG is set to FALSE, because WP_DEBUG really writes EVERYTHING (errors and warnings) and WP_DEBUG_LOG pushes all messages into the log file, as you can see in the core code ( load.php, wp_debug_mode()):

Depending on what is happening on the site, the log file can grow up within a very short time to an exporbitant size, up to gigabytes of data!

That’s why you should use WP_DEBUG_LOG only in places and don’t forget to change the lines in wp-config.php back to default.

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Hi! My name is Chris and I enthusiastically develop the web from back-end to front-end at Inpsyde. When I'm not discussing accessibility, you can find me at Google+. In my spare time I study computer science, do a lot of sports, read one book after the other and blog at www.chrico.info.

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