error after update to 1.3.23: strpos(): empty needle in /media.php on line 1088

Hmm, I'm not really sure.

Here's some things to try:

1. If you're using GP Premium, deactivate the Blog add-on - is the error still there?

2. If so, turn the Blog add-on back on and adjust the size of your images in "Customize > Blog > Post Images".

3. If the error persists, try re-uploading the image.

Let me know :)

None of the three solutions work on my blog ... the only way for me is to change from "false" to "true" at line 1088 of file "media.php in /wp-includes/

What about if you deactivate GP Premium and switch to TwentySixteen theme, still there?

It's a warning, so if you turn WP_DEBUG off it won't show on your site: https://codex.wordpress.org/WP_DEBUG

I have a feeling it's a WordPress bug as that topic I linked to has nothing to do with GP.

I had the same problem and also resorted to editing the media.php file

I was getting the error message on the page even with WP_DEBUG set to false

Never did figure out what was causing this - I assume it's a core WP bug, so changing the media.php file might be the best way until they end up fixing it (which should be very soon).

I have the same Problem with 4.4.2, any News for a Fix?

It might be caused by the responsive images in WordPress 4.4.

Try disabling them: https://wordpress.org/plugins/disable-responsive-images/

A Plugin to fix a Bug? :)
Sorry, but i want no additional Plugins in there...

You can use code as well, but it's the exact same thing as using a plugin: http://wordpress.stackexchange.com/questions/211375/how-do-i-disable-responsive-images-in-wp-4-4

It seems to be a WordPress bug, but only for some server set ups.

I am also getting this error in multiple locations:
https://oralhealthamerica.org/our-work/fall-for-smiles/downloads/

It's odd because it does not occur on the working site I used to initially set up GeneratePress:
https://oralhealthamerica.org/2016-wptheme/our-work/fall-for-smiles/downloads/

Both of these reside on the same server and refer to the same media.php file.

Installing the plugin to disable responsive images did not help.

Adding this line at the end of wp-config.php hides the error from your web page.

@ini_set('display_errors','Off');
(via WordPress forum)
or

@ini_set( 'display_errors', 0 );
(via Wordpress Codex)

Hope that helps others who face this problem.

Thanks for the info! This will disable the notices/warnings.

Still an odd error though, hopefully it's fixed in WP soon.

I notice the warning message in the server error log last month, but after changing the hosting service this week, the warning is now displayed in Web pages containing a featured image. May be a host-specific issue depending upon how PHP is configured. FWIW.

What's troubling most is that the warning contains the full location (including the root folder path) to WP-Includes. The root path and FTP user name might be (or "is") same in some hosts.

All PHP warnings/notices will show the path to the file with the issue, which is why it's important to use quality themes/plugins and have public notices disabled.