Fixing Error with Pow, RVM, Rack and Rails 3.1

After I updated a rails project to Rails 3.1 it seemed to suddenly stop working with my POW server. WTF?

I kept getting this error on my test site:

Error starting application

Your Rack app raised an exception when Pow tried to run it.

I am an RVM user and I knew it was something to do with that fantastical tool. It turned out I was right.

Even though I had activated Ruby 1.9.2 via RVM, it turns out POW needs to do the same thing. This is where .rvmrc files come in.

I basically generated an .rvmrc file for the project containing: rvm 1.9.2 and it worked fine after that. As usual, I found links after I solved the issue. See this github issue for more info on the solution.

Image Credit: Courtesy of the Boston Public Library, Leslie Jones Collection