Clearing caches kills the site

Sometimes it recovers, other times it does not and only a complete restore of both virtual host’s directory and DB restore BAU. This is, mildly speaking, infuriating.

Fatal error: Uncaught Error: Call to a member function switch_to_blog() on null in C:\WWW\host2\wp-includes\cache.php:343 Stack trace: #0 C:\WWW\host2\wp-includes\load.php(727): wp_cache_switch_to_blog() #1 C:\WWW\host2\wp-settings.php(131): wp_start_object_cache() #2 C:\WWW\host2\wp-config.php(99): require_once(‘C:\\WWW\\host2…’) #3 C:\WWW\host2\wp-load.php(50): require_once(‘C:\\WWW\\host2…’) #4 C:\WWW\host2\wp-blog-header.php(13): require_once(‘C:\\WWW\\host2…’) #5 C:\WWW\host2\index.php(17): require(‘C:\\WWW\\host2…’) #6 {main} thrown in C:\WWW\host2\wp-includes\cache.php on line 343

Fatal error: Uncaught Error: Call to undefined function __() in C:\WWW\host2\wp-includes\class-wp-recovery-mode.php:172 Stack trace: #0 C:\WWW\host2\wp-includes\class-wp-fatal-error-handler.php(52): WP_Recovery_Mode->handle_error() #1 [internal function]: WP_Fatal_Error_Handler->handle() #2 {main} thrown in C:\WWW\host2\wp-includes\class-wp-recovery-mode.php on line 172

Fatal error: Uncaught Error: Call to a member function switch_to_blog() on null in C:\WWW\host2\wp-includes\cache.php:343 Stack trace: #0 C:\WWW\host2\wp-includes\load.php(727): wp_cache_switch_to_blog() #1 C:\WWW\host2\wp-settings.php(131): wp_start_object_cache() #2 C:\WWW\host2\wp-config.php(99): require_once(‘C:\\WWW\\host2…’) #3 C:\WWW\host2\wp-load.php(50): require_once(‘C:\\WWW\\host2…’) #4 C:\WWW\host2\wp-blog-header.php(13): require_once(‘C:\\WWW\\host2…’) #5 C:\WWW\host2\index.php(17): require(‘C:\\WWW\\host2…’) #6 {main} thrown in C:\WWW\host2\wp-includes\cache.php on line 343

Fatal error: Uncaught Error: Call to undefined function __() in C:\WWW\host2\wp-includes\class-wp-recovery-mode.php:172 Stack trace: #0 C:\WWW\host2\wp-includes\class-wp-fatal-error-handler.php(52): WP_Recovery_Mode->handle_error() #1 [internal function]: WP_Fatal_Error_Handler->handle() #2 {main} thrown in C:\WWW\host2\wp-includes\class-wp-recovery-mode.php on line 172