[wp-trac] [WordPress Trac] #35340: PHP Fatal Error: Call to undefined method WP_Error::exists()

[WordPress Trac]

#35340: PHP Fatal Error: Call to undefined method WP_Error::exists()
--------------------------+-----------------------------
 Reporter:  crackhd       |      Owner:
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  Users         |    Version:  4.4
 Severity:  normal        |   Keywords:
  Focuses:                |
--------------------------+-----------------------------
 This error happens since update to Wordpress 4.4.0,
 my current version is 4.4.1 (not in the list in trac)

 Log:

 [Thu Jan 07 ... 2016] [:error] [pid 21932] [client...] PHP Fatal error:
 Call to undefined method WP_Error::exists() in /var/websites/s4mp/wp-
 includes/capabilities.php on line 505

 Fix:

 On line 505 in capabilities.php, change user_can() function from:
 ```
 if ( ! $user || ! $user->exists() )
         return false;
 ```
 To:
 ```
 if ( ! $user || $user instanceof WP_Error || ! $user->exists() )
         return false;
 ```

 When it happens?
 Enable "WP Maintenance mode" (with known plugin), then request password
 reset email and follow link. On my current configuration (without changes
 to Wordpress code) it raises this error when clicking "Submit" and sending
 password reset form.

 This of course not happens on clean Wordpress installation, this is list
 of my plugins (folder names):

 404-error-logger                                      custom-css-js-php
 rvg-optimize-database
 404-to-start                                          custom-sidebars
 site-plugin
 are-you-robot-recaptcha                               disable-search
 slate-admin-theme
 bbpress                                               easy-fancybox
 smart-donations
 bbpress-auto-suggest-topics-based-on-new-topic-title  easy-wp-smtp
 super-socializer
 bbpress-mark-as-read                                  email-users
 syntax-highlight
 bbpress-members-only                                  enhanced-text-widget
 tabby-responsive-tabs
 bbpress-permalinks-with-id                            google-analytics-
 dashboard-for-wp  tablepress
 bbpress-post-topics                                   hello.php
 twitter-tracker
 bbpress-quotes                                        index.php
 user-access-manager
 bbpress-report-content                                jetpack
 wordpress-seo
 bwp-recent-comments                                   jetpack-only-for-
 admins            wp-security-audit-log
 comments-widget-plus                                  login-with-username-
 or-email       zencache
 crayon-syntax-highlighter                             maintenance

 I could not find which of them causes problem exactly but error itself
 points to bug in wordpress, i think, because "$user" becomes an instance
 of "WP_Errror".

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Ticket URL: <https://core.trac.wordpress.org/ticket/35340>
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