Thin web server: `start_tcp_server': no acceptor (RuntimeError) after git branch checkout

Question

A Rails 3.2.0 app, working fine with Thin web server, both locally and on Heroku cedar stack.

After:

$ git branch work
$ git checkout work
$ rails se         


        

Answer 1

The port 3000 may already be in use. Look at http://mrjaba.posterous.com/starttcpserver-no-acceptor-runtimeerror