Recently debug.log (WP 5.3.2) grew to 17GB because of tons of entries like this:

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 1 in /wp-includes/media.php on line 790

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 0 in /wp-includes/media.php on line 69

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 1 in /wp-includes/media.php on line 70

What would be an efficient way to find out what exactly causes these notices?

Recently debug.log (WP 5.3.2) grew to 17GB because of tons of entries like this:

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 1 in /wp-includes/media.php on line 790

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 0 in /wp-includes/media.php on line 69

[17-Jan-2020 16:29:01 UTC] PHP Notice: Undefined offset: 1 in /wp-includes/media.php on line 70

What would be an efficient way to find out what exactly causes these notices?

• php
• debug
• core

• 1 Try disabling plugins and/or changing theme. One of them is passing incorrect $size array when calling functions in media.php. – Vitauts Stočka Commented Jan 21, 2020 at 16:27
• 1 You can also check for empty $size arrays at those places and log the wp_debug_backtrace_summary to see where the bad calls came from. – Rup Commented Jan 21, 2020 at 23:34
• It was a plugin misbehaving indeed... problem solved. With thanks. – chris Commented Jan 22, 2020 at 15:35

1 Answer 1

I know it was mentioned in the comments that you solved this by locating the offending plugin. However, I thought the following answer may be helpful for others if they happen along this in a search.

Here's a little code snippet that can be used to save the debug log file by date:

ini_set( 'error_log', WP_CONTENT_DIR . '/debug-' . date('Y-m-d') . '.log' );

Using this method, you can prevent the file from just growing (it will set a new one each day).

Obviously, you want to track down the real problem so the debug log doesn't grow infinitely. But using something like this can buy some time to help during the process.