Yes, this happened to me today as well. I deactivated the plugin as well. Once I did, my site loaded beyond the initial login page. I’ve decided at this point, it’s not worth it to activate the plugin again.
Thank you – I am using the latest version of WordPress. It did not resolve the issue. When I tried to activate the plugin, absolutely nothing happened. So I tried to delete it and it wouldn’t allow me to delete the plugin saying it was activated but in the plugins area it will still showing as inactive.
I was finally able to delete it and then reinstall it. However, I got the same notice that said, “The plugin generated 3 characters of unexpected output during activation. If you notice “headers already sent” messages, problems with syndication feeds or other issues, try deactivating or removing this plugin.”
I have left the plugin installed but I notice that any time I make a change in admin and then save, the admin panel goes completely blank. The only way I am able to retrieve my site is to re-enter the site name and “/wp-admin/index.php”.