My Game has suddenly stopped packaging, Please help! D:

My game has all of a sudden just stopped packaging now as automation tool exits with code 25 - unknown cook failure. I have no idea how to fix this, I have a feeling it’s something to do with the Steam Subsystem but if anyone could point me in the right direction I would really appreciate it.

Did you look at the build log? The tool should be generating an UnrealBuildTool log with more information.