If you’re trying to install rack-mini-profiler and it’s missing in production, the likely cause is the order of your middleware.
Run this command
RAILS_ENV=production rake middleware
And then double check that that the Rack::MinProfiler is after any “deflating” middlewares.
This worked for me:
# CRITICAL TO DO THIS REQUIRE require 'rack-mini-profiler' # CRITICAL that we load MiniProfiler after the Deflators # See https://github.com/MiniProfiler/rack-mini-profiler/issues/134#issuecomment-126648241 if Rails.env.production? or Rails.env.staging? Rails.application.middleware.delete(Rack::MiniProfiler) Rails.application.middleware.insert_after(HerokuDeflater::SkipBinary, Rack::MiniProfiler) end
Here are a few related issues. This is a yak shave for many:
The tool is good enough and popular enough that I deem this effort a worthwhile, albeit a painful, endeavor!