After googling a lot, I just delete that file and restart the server. Then again system create that file, then again I delete that file. Now Server is running fine. And System generates another copy at the same place. But it is running well.
DELETE THAT FILE ....
If you want to run two servers then it may again create trouble. So
Both commands are checking the default PID file location (tmp/pids/server.pid), so you’re seeing this error. Try running multiple servers like so:
Server 1: bundle exec rails s
Server 2: bundle exec rails s -p 3001 -P tmp/pids/server2.pid
Credit: https://stackoverflow.com/a/14446920/1376448
Thanks
UPDATE after Connor Leech comment about Forman Gem
Foreman can help manage multiple processes that your Rails app depends
upon when running in development. It also provides an export command
to move them into production.