The TypoScript setup variable plugin.tx_seminars_pi1.hideColumns contains the value "status", but only the following values are allowed:
(image, category, title, subtitle, uid, event_type, accreditation_number, credit_points, teaser, speakers, language, date, time, expiry, place, city, seats, country, price_regular, price_special, total_price, organizers, target_groups, attached_files, vacancies, status_registration, registration, list_registrations)
This value specifies which columns to remove from the list view. Incorrect values will cause the columns to still be displayed. Please fix the TypoScript setup variable plugin.tx_seminars_pi1.hideColumns in the plugin Flexforms or in your TypoScript template.
The configuration check for this extension can be disabled in the extension settings in the backend: Admin Tools > Settings > Extension Configuration