Hello,
I am getting the same error. I have installed the same version, on WordPress 4.9.6. It breaks the site and cannot acces anyway the dashboard. I had to erase manually your plugin so as to be able to access the WP dashboard again.
I have been searching in this forum, reading your advises to reset permalinks… I have tried to get them configured in every available option… nothing! not working)… Another thread like this: https://wordpress.org/support/topic/404-page-found-with-new-url/ (quite ‘original’!), and once I reactivate your plugin, breaks again!
We have another sites with previous versions of yours and they do work.
Hope you can help me. Thanks in advance!