As Eris Market Fix is for 2.1 Eclair only, here is how to fix JP3 manually. Amend the following lines in /system/build.prop. (make sure you make a copy before you edit it. It is also advise to do a nandroid backup)


ro.build.description=GT-I9000-user 2.1-update1 ECLAIR XWJG1 release-keys
ro.build.fingerprint=Samsung/GT-I9000/GT-I9000/GT-I9000:2.1-update1/ECLAIR/XWJG1:user/release-keys

Reboot phone and see the protected app in market :)

Note: What we do here is tell market that the phone is running 2.1 XWJG1, so beware when you download apps as Market will now also show Froyo incompatible apps.