Can't upload anything – 404 Not Found Error

I installed the plugin and went to imports > page > from computer – Browse – click on csv page and when the green bar finished, then I click on Next.

Then it opens my website with a 404 Not Found error.

I can’t get to the next page to map CSV and WP fields.

My CSV consist of post_title; post_slug; post_status; columns only – (I just want published pages with no content or anything else.)

What am I doing wrong?

Thank you!

My site:
http://dir.satravel.info/

Jen

https://wordpress.org/plugins/wp-ultimate-csv-importer/