Couldn't find local trustcache

[teddysnp]

I want to downgrade my iphone6s from 13.3 to 11.3 with pyboot 0.3, I got problem:Couldn't find local trustcache.

$ ./pyboot.py -q iPhone_4.7_11.3_15E216_Restore.ipsw iPhone8,1

...

ttps://api.ipsw.me/v4/device/iPhone8,1?type=ipsw Getting SHSH for signing images Moving iBSS/iBEC... dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool dyld: Symbol not found: ____chkstk_darwin Referenced from: /Users/mymac/PyBoot-master/./resources/bin/img4tool Expected in: /usr/lib/libSystem.B.dylib in /Users/mymac/PyBoot-master/./resources/bin/img4tool Largest file is 058-97232-127.dmg, getting correct trustcache... ERROR: Couldn't find local trustcache