Ubuntu – Receiving error while trying to debug in QtProject

ccompilingdebuggingqt

I installed the latest version of the QtProject so now I can debug C++ code.

While trying to debug for the first time I got this error:

ptrace: Operation not permitted.

Could not attach to the process. Make sure no other debugger traces this process.
Check the settings of
/proc/sys/kernel/yama/ptrace_scope
For more details, see /etc/sysctl.d/10-ptrace.conf

Best Answer

On Ubuntu versions after 10.10 you'll run into this in more related applications, such as QtCreator. It is a security feature of Ubuntu that prevent the debugger to attach to processes not owned by him.

This is filed as a bug #3509 against QtCreator. To work around this issue, do this:

  • temporary solution (won't survive a reboot):

     echo 0 | sudo tee /proc/sys/kernel/yama/ptrace_scope
    
  • In a file /etc/sysctl.d/10-ptrace.conf (should already exist), change the value of kernel.yama.ptrace_scope to 0 and then reload the configuration: sudo sysctl -p.

I'm explicitly posting the temporary solution, as you probably don't want to keep this feature disabled on a regular machine for security reasons.