"This curriculum no longer exists: it may have been moved to the trash."

Where: adding a note on a student's progression page, the Note sheet of a session, or choosing a group's curriculum.

Why: the chosen curriculum no longer exists for the school: it was moved to the trash (by the owner) while the screen was open, or it belongs to another school.

What to do: close the sheet, reload the screen to get the current list, then choose a curriculum that is still there. The owner can restore a curriculum from the Trash for 30 days.