How can accept only .csv files? I have seen that having a condition like When File uploader's file name contains .csv is used by many, but what happens when a user uploads a .mp3 file named 1.csv.mp3, that condition would be passed, so it is not a viable option for me.
In general, for CSV choose the comma. (c stands for comma).
I haven’t tried but is the operator :truncate from end to available? If so you could use something like when ‘file’s name :truncated from end to 4 is .csv’