local musget = http:PostAsync(trello api request http:JSONEncode({["name"]=(plr.Name .. " | ".. plr.userId), ["desc"] = data,["due"]=nil,["idList"]=boardid,["urlSource"]=nil}))
The 'data' variable is all the questions combined in a variable. The thing is, the error says 'cannot convert to to json' when trying to jsonencode. IF i change desc to lol, it sends the card to trello perfectly with the description 'lol'. I found a post on this made in 2015 on the roblox scripting forums, but there was no fix.
EDIT: Heres the code that makes data.
local data = ""
for i=1, #module.Questions do
data = data .. "\
".. script.Parent.p3.ScrollingFrame["q"..i].TextLabel.Text .. ": ".. script.Parent.p3.ScrollingFrame["q"..i].TextBox.Text
end
Printing data works as intended: prints the questions and answers to questions.

4 comments
Testing right now. Will accept answer if it works.
It seems this does not work: the nils are fine. The desc = data part fails to encode: if I change data to "" it doesen't fail to encode. But data is a string in a variable.
Are you confident every part of data is a string? Would you mind posting the code that creates data so we can better help you?
Edited.