In case you run into issues here are a few tips that can help you diagnose the problem.

Generally, it’s not a bad idea to configure Emacs to spit the backtrace on error (instead of just logging the error in the Messages buffer). You can toggle this behavior by using M-x toggle-debug-on-error.

Debugging Projectile commands

Emacs features a super powerful built-in Emacs Lisp debugger and using it is the best way to diagnose problems of any kind.

Here’s a great crash course on using the debugger.

To debug some command you need to do the following:

  • Figure out the name of the command you want to debug (e.g. by using C-h k to see which command is associated with some keybinding)

  • Find the source of the command (e.g. by using M-x find-function RET function-name)

  • Press C-u C-M-x while in the body of the function

  • Run the command again

At this point you’ll be dropped in the debugger and you can step forward until you find the problem.

Profiling Projectile commands

Emacs comes with a built-in profiler. Using it is pretty simple:

  1. Start it with M-x profiler-start.

  2. Invoke some commands.

  3. Get the report with M-x profiler-report.

If you intend to share the profiling results with someone it’s a good idea to save the report buffer to a file with <kbd>C-x C-w</kbd>.

Commonly encountered problems (and how to solve them)

Using some command causes Emacs to freeze for a while

Sometimes a Projectile command might hang for a while (e.g. due to a bug or a configuration issue). Such problems are super annoying, but are relatively easy to debug. Here are a few steps you can take in such situations:

  • Do M-x toggle-debug-on-quit

  • Reproduce the problem

  • Hit C-g around 10 seconds into the hang

This will bring up a backtrace with the entire function stack, including function arguments. So you should be able to figure out what’s going on (or at least what’s being required).

I upgraded Projectile using package.el and nothing changed

Emacs doesn’t load the new files, it only installs them on disk. To see the effect of changes you have to restart Emacs.