Magento ver. 2.2.0-dev - A technical problem with the server created an error. Try again to continue what you were doing. If the problem persists, try again later.
Magento 2018-08-01 15:19:08 5238
I got the same error (Magento 2.2.0, ngix). But only for backend-users with limited access (catalog and customers). There is no error messages in the admin-account. All available backend-pages are contaminated. There is no deleted store-view as mentioned
Display notification messages in Magento 2
Magento 2018-05-11 01:47:33 1240
How to display confirmation messages, error or warning to the user is something every theme and/or Magento 2 extension developer should know about. There are four types of notification messages you can use: Error (in red), Notice (yellow), Success (green)