I have created a collision section in several site (visit.cern, voisins.cern), but I am unable to reproduce it on test-guides.cern.ch…
I have a content type “event” with a title, a start and a end date.
The Agenda Box view mode exists
I have matched my “event” content type fields with the “Agenda Box” pattern
I have created a Block view based on the “event” content type with Collision format.
But if I pick “Agenda Box” as the display Suite Content type, the preview returns nothing and my home page displays the following error: The website encountered an unexpected error. Please try again later.
I have temporarly selected “Preview Card” to allow my langing page to be accessed… But I would like to have the normal collision format.
All the settings for the view and the display suite etc are perfect. The error "The website encountered an unexpected error. Please try again later." is often faced due to some glitch (Sometimes while installing a module, cache, adding new functionality, from the server side, custom code, php config etc.).
If only one page is showing this error and admin is working then try checking reports → Recent log messages (/admin/reports/dblog) to see the error log and solve the issue. Though the best way to retain things to normal would be restore your website to a previous backup, flush out the caches and then implement the changes you want.