$wp_plugin_paths is null in plugin_basename

[dsawardekar]

While upgrading to 3.9.0 I noticed a few PHP notices in plugin.php. The
upgrade was successful but I have strict error reporting turned on in
PHP that showed up these errors.

Warning: Invalid argument supplied for foreach() in /var/www/wp-dev/wp-includes/plugin.php on line 623

I'm using PHP 5.5.3 on Ubuntu, with individually symlinked plugins in
wp-content/plugins.

Further investigation revealed that the cause is to do with parent
directory extraction in the plugin_basename method.

Attached is a patch that adds a null check to the for loop that makes
this Notice go away.

[dsawardekar]

Patch with NULL check for $wp_plugin_paths

[Otto42]

Lots of reports of issues with this over the past few days:

​https://wordpress.org/support/topic/invalid-argument-supplied-for-foreach-30?replies=15

Warning: Invalid argument supplied for foreach() in ... wp-includes/plugin.php on line 622

Related: #16953

Not certain about root cause yet, but I think a partial upgrade may be at fault.

[SergeyBiryukov]

Related: comment:105:ticket:16953

[nacin]

This is a very good indication that wp-settings.php was not updated as part of the update. I'd rather not suppress this error as it could just make the next support question even more opaque.

[dsawardekar]

Not sure if it's a partial install issue. I did a diff of the relevant files with the 3.9.0 tag to verify. No changes were detected.

Anyway I disable error reporting on production sites. Haven't seen this in production so far. So it's a development only issue I suppose.

[rmccue]

Replying to dsawardekar:

Not sure if it's a partial install issue. I did a diff of the relevant files with the 3.9.0 tag to verify. No changes were detected.

wp-settings.php should have $GLOBALS['wp_plugin_paths'] = array(); on line 167.

The only other thing I can think of is that you somehow have a customised wp-settings.php, or you're loading WordPress without loading this. We've seen this issue pop up before with WP-CLI, which uses a custom wp-settings.php and had to be updated to match.

[dsawardekar]

@rmccue Upgrading WP-CLI to dev-master did the trick. Thanks!

[SergeyBiryukov]

#28430 was marked as a duplicate.