TWRP Failed to mount '/system' (Invalid Argument)?

[stantse1]

I was trying to install Cyanogenmod 12.1 on my Samsung Galaxy J5 sm J5008, but TWRP couldn't mount '/system'. I've tried changing it to file structures like EXT4, FAT, exFAT and F2Fs, but no luck. Now I formatted my internal storage, so I have absolutely nothing in my phone right now. I think the best workaround would be to fix the mounting issue, as I might have trouble installing the stock ROM through Odin.

Any suggestions?

 

[B. Diddy]

Moved to the new J Series forum.