They don’t seem to read these forums. I’ve came across the same problem, because I changed my user admin ID in database.
To make everything working again, just login to your database, find table
wp_easycontactforms_users
edit the first one, with the description “Admin” and change CMSid to the userID which you are using.
If you dont know which ID is it, you can check it in the wp_users
I am having the same issue. And it seemed to just pop up. I am the only admin, and the only editor of the site and plugins. So what gives? Why can’t Easy Contact Forms just update the damn plugin? I see reports of this from 2 years ago. I have looked at the _users php file and am not sure what line to edit as no one really tells you where the code is or the exact code to replace it with.