Problem Starting Ruby on Rails WEBrick Server

Today I encountered an interesting problem and one that was a first for me.  I was testing my Rails app and started the WEBrick server.  I then received the following error message:

[2006-04-12 23:01:13] INFO  WEBrick 1.3.1
[2006-04-12 23:01:13] INFO  ruby 1.8.2 (2004-12-25) [i386-mswin32]
[2006-04-12 23:01:13] WARN  TCPServer Error: Only one usage of each socket address (protocol/network address/port) is normally permitted. - bind(2) c:/program files/ruby/lib/ruby/1.8/webrick/utils.rb:62:in `initialize’: Only one usage of each socket address (protocol/network address/port) is normally permitted. - bind(2) (Errno::EADDRINUSE)

It turns out that an existing process had a hold of port 3000.  While I had no clue what could possibly be using this port I started looking through my processes one-by-one.  I finally realized the only difference in my environment today was that I was on my PC and ActiveSync was currently running.  This was the first time I ever tried starting WEBrick with my phone docked.  It sounds completely unrelated, but it turns out that ActiveSync had a lock on port 3000 and disconnecting my device solved the problem.  I’m certain there’s a way to start WEBrick on another port, but I have a workaround for now.  I wanted to post this to prevent anyone else from wasting an hour trying to figure out what’s going on.

One Response to “Problem Starting Ruby on Rails WEBrick Server”

1. Edward says:

   June 8, 2006 at 7:30 am

   ActiveSync was indeed my problem - as soon as I removed my iPaq from its cradle it worked.

   Many thanks.