The title says it all. I had just completed a milestone in my code and thought, "Hey, there are a few security patches available for Rails, what a perfect time to upgrade." So I did what has become automatic behavior at this point: pop open a terminal and type brew update && brew outdated

"Oh, look," I said to myself, "I can update rbenv, ruby-build, nginx, git and mercurial as well!"

Bad idea...

A quick trip to the coffee pot and a little compiling later, all the updates were completed. Yay. My apps were humming along fine and everything seemed to Just Work™ Then it happened. Everything stopped working. Why? Pow seemed to no longer understand that I wanted to use Ruby 1.9 for my app and insisted on loading Ruby 1.8. Meanwhile in my terminal everything loaded properly. What gives?!

By now you can see why doing all the updates at once was a terrible decision. Which one of them was the culprit? Why did it suddenly happen at this very moment after everything seemed to have been working just moments before? I was in for a lot of poking and checking and searching. Here's what I ended up doing (short version) and what eventually was the ultimate culprit and how I fixed it. Hopefully this write-up will help someone else, should they find themselves in the same situation.

• First, check that everything is actually working in the terminal. rails c, no errors. rails s loads, site functions fine.
• Run through installed Ruby Gems. Look for outdated ones that may be incompatible, get the latest ones installed and run bundle upgrade so it can rewrite Gemfile.lock. Restart the app. Still nothing.
• Start looking into .powconfig to see if anything has changed. Hmm, looks like I can use the new rbenv root command to avoid hard coding my home directory path. Nice. Still no luck.
• Find out that because I'm using Homebrew to manage my rbenv and ruby-build installs, I need to actually reference brew --prefix rbenv for the bin directory, while the shims directory remains in my home directory. Update, restart Pow. Nothing.
• Reboot the machine, walk away to clear head, go to geeky meetup, have lots of beer.

The next morning.

• $PATH has my shims directory in it twice, look through ZSH configs. Find I had manually added it to the path when I originally switched to ZSH from a recommendation found online. Removed that.
• Kept digging through configs, found an rbenv method that was supposed to make it work in non-interactive shells. Maybe that's the culprit! Removed, restarted Pow, nothing.
• Felt like I was going in the right direction, dug for more duplication, cleaned up configs, made my dotfiles better... still no love.
• Opened a new terminal and randomly decided to type rbenv version (even though I know what version is running as it's displayed in my prompt) and saw

  1.8.7-p370 (set by /Users/seth/.rbenv-version)
  

  Hmm, the latest rbenv prefers the more portable .ruby-version files. Let's update that. rm .rbenv-version...

For giggles I restarted Pow, loaded the site... and it worked. And fast (hurray for Rails update?) Huh, maybe there's a bug with using the old .rbenv-version file but just to check, rbenv local 1.8.7-p370, restart Pow, fail. So there it is. Finally found.

I haven't dug into the code to figure out why this is yet but it now seems rbenv chooses the .ruby-version file in home instead of the one in your project directory. The only fix I found was to simply not use a local version file in your home directory.

Mystery Solved.

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Silver lining: I made a bunch of little tweaks and changes to my dotfiles, removed redundancy and overall my apps and terminal feel faster from it. Yay.