the problem is already known, that gdb doesn't work with OS X Sierra anymore.
This is really annoying, since I researched already about the solution, and there were some solutions, but they apparently don't work anymore. I tried to use the .gdbinit file solution and the disable csrutil solution, both doesn't work.
Sooo my question is: Does anyone know how to fix it in 10.12.3 ?
Thank you very much!
So thanks to Basile Starynkevitch, who just gave me the idea to update gdb
You simply have to update gdb for the latest version (which is 7.12.1 currently). Assuming you have installed Homebrew:
That's what I did:
brew update brew remove gdb brew install gdb
It has now updated to the latest version.
Now codesign gdb again with the cert that you used before.
sudo killall taskgated codesign -fs gdb-certi /usr/local/bin/gdb launchctl load /System/Library/LaunchDaemons/com.apple.taskgated.plist
Last step is still to use the workaround to create the .gdbinit file:
set startup-with-shell off
Debugging works for me now :) (OS X Sierra 10.12.3 - gdb 7.12.1).