Hello victorialove,
Thanks for going Pro and welcome to the forums! I’m sorry you are experiencing an issue, let me try to help you with that.
Thank you for submitting your system information. Based on that I see that you The Events Calendar has an older version than Events Calendar Pro. Please update The Events Calendar and see if the issue still persists.
If you are doing an automatic update, then you can try deactivating the Pro or even both plugins before that. If there is an error with the update, then as a next step log in to your server and delete the the-events-calendar/lang/the-events-calendar-de_DE.mo file, and try the update afterwards.
If you want, you can also do a manual update. Just follow the steps in this knowledgebase article on our site: https://theeventscalendar.com/knowledgebase/manual-updates/
And it is recommended to do a backup before doing any update on the site. There are a number of good free and pay-for plugins for this purpose.
Let me know if you manage to solve this or if you have any other questions.
Cheers,
Andras