The line you reported (…/newsletter/do/view.php) is not part of the subscription process but I don’t know why that page is activated and more it should not show that error message, it means the plugin is not active!
Bye, Stefano. Already tried Nearby Photos? Try it and see what’s happening around you!
That didn’t really help me much :/ The plugin is set to active (tried deactivating it and then reactivate it but obviously no change). Don’t want to delete/re-install and lose all my current subscriber information. So strange when it used to work without any problems. Hopefully I will figure it out somehow.