Vanilla 2.6 is here! It includes security fixes and requires PHP 7.0. We have therefore ALSO released Vanilla 2.5.2 with security patches if you are still on PHP 5.6 to give you additional time to upgrade.
Have you take a look at the Vanilla 2 Upgrading Tips post?
Try re-uploading the files again and then visit /utility/update. You may run this more than once.
Do you have RewriteUrls enabled for_… (View Post)