Celery + Django: Cannot start celerybeat on Windows 7
Search your file system for that pid file and delete it. On unix machines that usually means the program was not shut down correctly. You should check to see if its running in the task manager already, if so kill it, and delete that file
Then try again.
If there is no pid file present, that probably means there's an issue with the software as it was ported from unix perhaps?
In my case of django project on Windows this file was already existing in root of the Django project. I deleted that file and the process ran without any error.
The "celerybeat.pid" was already existing because I ran celery beat from another PC and pushed the git repo to the cloud. When I pulled the repo on my working PC and ran the process, it gave me error referring to the file "celerybeat.pid" created earlier by another PC. Deleting the "celerybeat.pid" made it work.