You've provided the pak file name in command line. It's wrong, you can't do this. You can only provide PACKAGE names there (uasset names). UModel attempts to treat pak file as uasset, but it won't work with uassets which are larger than 2Gb, and displays THIS error message.
In order to load pak file, you should specify path to it, with -path=... option. If multiple pak files will be found, they all will be loaded.
Also, "-all" option is very obsolete. Right now it could be used only in conjunction with -dump option.
If you want to export everything from pak(s), you should use something like this:
umodel -path=c:/my_paks -export *.uasset