Updating to 6.x-2.18 causes errors, whitescreening, SQL errors, general mayhem

I have a Drupal 6 multisite. The version of Views in sites/all/modules remains at 6.x-2.16. To update two of my test sites, I dropped a copy of 6.x-2.18 into sites/[localsite]/modules.

Following this, if you try to go to Views, you get a white screen, followed by,

warning: call_user_func_array() expects parameter 1 to be a valid callback, function 'views_access' not found or invalid function name in /var/www/drupal-6.34/includes/menu.inc on line 454.

warning: Invalid argument supplied for foreach() in /var/www/drupal-6.34/sites/all/modules/views/includes/view.inc on line 1800.

user warning: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') ORDER BY vid, position' at line 1 query: load_views /* memcinto : load_views */ SELECT * FROM views_display WHERE vid IN () ORDER BY vid, position in /var/www/drupal-6.34/sites/all/modules/views/includes/view.inc on line 1419.

and then finally the whole site starts whitescreening. Multiple "drush cc all" etc had no effect.

When I removed the 6.x-2.18 version of Views from the local site folder, it took a while, but the site finally came back. All views-created blocks had been disabled and had to be re-placed. Views-created pages were throwing "page not found" until I went and edited each one and saved it.

If Views can't be updated by adding an updated version to the local site module folder, then I guess I will just have to update it in sites/all/modules and hope for the best. (Not.)