I recently created a new Rails project after installing Ruby and Rails on Windows with RailsInstaller. In my gemfile, I reference bcrypt like this:
gem 'bcrypt', '~> 3.1.7', platforms: :ruby (I added the platforms: :ruby, without server won't start with the same error as described further below)

The server can be started, no problems here, but wen instantiating a model with has_secure_password I get the following error message:

You don't have bcrypt installed in your application. Please add it to your Gemfile and run bundle install
Completed 500 Internal Server Error in 16ms (ActiveRecord: 0.0ms)

LoadError (cannot load such file -- bcrypt_ext):

app/models/access.rb:2:in <class:Access>' app/models/access.rb:1:in <top (required)>'
Rendering C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout
Rendering C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb
Rendered C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_source.html.erb (3.0ms)
Rendering C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb
Rendered C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_trace.html.erb (1.0ms)
Rendering C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb
Rendered C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/_request_and_response.html.erb (1.0ms)
Rendered C:/RailsInstaller/Ruby2.3.0/lib/ruby/gems/2.3.0/gems/actionpack-5.0.1/lib/action_dispatch/middleware/templates/rescues/diagnostics.html.erb within rescues/layout (358.0ms)
Exiting

I tried fixing the version of bcrypt to 3.1.9, because I found this issue where a similar error occurred for the 3.1.7 and the solution was to use 3.1.9, but this didn't help at all, on the contrary: Afterwards the server wouldn't start at all.

I know there is Issue 142, but their solution doesn't work for me.

Does anyone have an idea how I could fix this?