How does spoofing upvalues work exactly?

[ishqpyari]

Maybe try this link:

Upvalues Overwritten

Causing any ‘Lua’ error (not from ROBLOX libraries or error functions) will overwrite every upvalue to some weird values. Usually numbers, threads and nil; depending on where the upvalue was indexed. Reproduction code: local x = "Hi" coroutine.resume(coroutine.create(function() while wait() do print(x) end end)) a() Output: > error: attempt to call global 'a' (a nil value) > 367 > 367 > 367 > 367 ... This is not a new bug. I went through this problem 1 year ago but didn’t know the exact c…