Yesod -- devel.hs: connect: does not exist (Connection refused)

I'm moving a web app to a new server and upgrading the project from Yesod 1.2 to 1.4. When I ran yesod devel I got the following error:

Starting development server...
Starting devel application
Devel application launched: http://localhost:3000
devel.hs: connect: does not exist (Connection refused)
Exit code: ExitFailure 1

I'm not sure how to debug this quickly. This is running on Ubuntu 14.04 x64. I'm able to run another web server on port 3000.

Solution

I tracked it down to using Database.Memcache.Server but not having memcached running. The Yesod upgrade wasn't related.