Attempt to load ...

[undefined]

local dff = engineLoadDFF(dff_file) 
local result = engineReplaceModel(dff, modelID) -- Line 54 

What is the meaning of this warning?

[KariiiM]

That's mean the 42.dff file is failed to load before the trigger of the event onClientFileDownloadComplete

[undefined]

How can I prevent it?

[Walid]

Show me your code