A server is already running. Check …/tmp/pids/server.pid. Exiting - rails

Question

..$ rails s
=> Booting WEBrick
=> Rails 4.0.4 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=>         


        

Answer 1

SOLVING

Address already in use — bind(2)” 500 error in Ruby on Rails

Recently I tried running a Rails app on a production server. Not only did it not work, but it broke my localhost:3000 development server as well. Localhost would only load a blank white page or a 500 error.

To solve this, I used two quick commands. If these don’t return a result, you may need to look elsewhere for a solution, but this is a good quick fix.

lsof -wni tcp:3000

ruby    52179 rachelchervin   50u  IPv6 0x...7aa3      0t0  TCP [::1]:hbci (LISTEN)
ruby    52179 rachelchervin   51u  IPv4 0x...c7bb      0t0  TCP 127.0.0.1:hbci (LISTEN)
ruby    52180 rachelchervin   50u  IPv6 0x...7aa3      0t0  TCP [::1]:hbci (LISTEN)
ruby    52180 rachelchervin   51u  IPv4 0x...c7bb      0t0  TCP 127.0.0.1:hbci (LISTEN)

This command shows all of my currently running processes and their PIDs (process IDs) on the 3000 port. Because there are existing running processes that did not close correctly, my new :3000 server can’t start, hence the 500 error.

kill 52179

kill 52180

rails s

I used the Linux kill command to manually stop the offending processes. If you have more than 4, simply use kill on any PIDs until the first command comes back blank. Then, try restarting your localhost:3000 server again. This will not damage your computer! It simply kills existing ruby processes on your localhost port. A new server will start these processes all over again. Good luck!