stack.sh failing giving error "g-api did not start"

same issue i faced , tried with ./unstack.sh and ./clean.sh also but couldn't fix the issue.
Following step helped me to resolve this issue.
./unstack.sh
./clean.sh

rm -rf devstack folder

reboot system

cloned devstack code
cd devstack
./stack.sh

ref: https://bugs.launchpad.net/devstack/+bug/1119428