It seems like a decent amount of the posts on this forum are from people who have problems running code that is outdated, which I'm guessing they copied off previous older projects or old tutorials.

Perhaps it would be useful if oTree could detect some of the more common mistakes and warn users in console when running devserver.

Off the top of my head and from what I noticed just on the first page: creating_session inside the Subsession class, (any other functions that were moved like the creating_session?), detect if people name the variable in a page function 'self' and warn them that 'self' is not used anymore and the given parameter is actually of type 'player', or whatever it is for that specific function.

Best,
Rok