Some people, like me, have experienced a problem: Being unable to save the hacked firmware for their GH1 (or GH2, I assume) with Ptool, because it just keeps insisting that "bad file name, camera won't be able to read such a file". This, even if the naming follows the rules exactly (in the vein of GH1__133.bin), and nothing seems to help.

I do not know if anybody has reported the solution before, at least I could not find one here or the rest of the internet, but I faced this problem today and eventually found a fix.

The solution is that the SOURCE firmware, the one you load at the beginning, needs to be correctly named as well. When the problem happened to me, I had made a copy/paste duplicate of the very original Panasonic firmware that I had downloaded from the internet. This had resulted to a source filename "GH1__132 - Copy.bin"

One would imagine that it makes no difference, as PTool requests the user to give a name when saving and that is the only thing that has to pass the validity check. However, for some reason the original filename, probably "-" or " " character, echoes the saving procedure and the validity test is failed. For instance, when I finally tested renaming the source firmware first back to "GH1__132.bin and then saving it with the name"GH1__133.bin", it was suddenly again very acceptable name and finally got my hacked firmware saved.