[wp-trac] [WordPress Trac] #54969: PHP Fatal error when upgrading WordPress to 5.9

[WordPress Trac]

#54969: PHP Fatal error when upgrading WordPress to 5.9
-------------------------------------+------------------------------
 Reporter:  garak734                 |       Owner:  (none)
     Type:  defect (bug)             |      Status:  new
 Priority:  normal                   |   Milestone:  Awaiting Review
Component:  Upgrade/Install          |     Version:  5.9
 Severity:  normal                   |  Resolution:
 Keywords:  close reporter-feedback  |     Focuses:
-------------------------------------+------------------------------

Old description:

> Clicked on manual upgrade link on dashboard to upgrade from 5.8.2 to
> Version 5.9-en_GB.
>
> Message on screen: There has been a critical error on this website.
>
> Error message in debug.log:
>
> PHP Fatal error:  Uncaught Error: Call to a member function
> switch_to_blog() on null in C:\wamp64\www\xxxxxx\wordpress\wp-
> includes\cache.php:239
> Stack trace:
> #0 C:\wamp64\www\xxxxxx\wordpress\wp-includes\load.php(727):
> wp_cache_switch_to_blog(1)
> #1 C:\wamp64\www\xxxxxx\wordpress\wp-settings.php(131):
> wp_start_object_cache()
> #2 C:\wamp64\www\xxxxxx\wordpress\wp-config.php(116):
> require_once('C:\\wamp64\\www\\x...')
> #3 C:\wamp64\www\xxxxxx\wordpress\wp-load.php(50):
> require_once('C:\\wamp64\\www\\x...')
> #4 C:\wamp64\www\xxxxxx\wordpress\wp-admin\upgrade.php(18):
> require('C:\\wamp64\\www\\x...')
> #5 {main} thrown in C:\wamp64\www\xxxxxx\wordpress\wp-includes\cache.php
> on line 239

New description:

 Clicked on manual upgrade link on dashboard to upgrade from 5.8.2 to
 Version 5.9-en_GB.

 Message on screen: There has been a critical error on this website.

 Error message in debug.log:
 {{{
 PHP Fatal error:  Uncaught Error: Call to a member function
 switch_to_blog() on null in C:\wamp64\www\xxxxxx\wordpress\wp-
 includes\cache.php:239
 Stack trace:
 #0 C:\wamp64\www\xxxxxx\wordpress\wp-includes\load.php(727):
 wp_cache_switch_to_blog(1)
 #1 C:\wamp64\www\xxxxxx\wordpress\wp-settings.php(131):
 wp_start_object_cache()
 #2 C:\wamp64\www\xxxxxx\wordpress\wp-config.php(116):
 require_once('C:\\wamp64\\www\\x...')
 #3 C:\wamp64\www\xxxxxx\wordpress\wp-load.php(50):
 require_once('C:\\wamp64\\www\\x...')
 #4 C:\wamp64\www\xxxxxx\wordpress\wp-admin\upgrade.php(18):
 require('C:\\wamp64\\www\\x...')
 #5 {main} thrown in C:\wamp64\www\xxxxxx\wordpress\wp-includes\cache.php
 on line 239
 }}}

--

Comment (by SergeyBiryukov):

 Looking at the error log, it seems like the `$wp_object_cache` global was
 not properly initialized for some reason.

 Are you using an external object caching plugin?

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/54969#comment:3>
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