When you run "rails s -b 0.0.0.0" into a bash command console and the Rails Server does not start, look at the logs and determine what the error is. If you can't pinpoint exactly what the error is saying, try to remember what you did before you shut off Rails Server. Below are the possibilities of what could be going on: Check in your routing.rb file and see if there are any lines of code that are not supposed to be in there Check in your development.rb file in the Environment Folder for any lines of code that is not suppose to be in there (This folder contains environment files that sets whether the environment you are working in is a development, staging or production) Lastly, if you haven't resolved the issue yet, try to copy the error and paste it in Google Search, remember Google Search is like a database, know the tips and tricks to the different styles of googling. That is how you find information, try to change how you query/search. If you don't find the answers try to change the wording of your query or wrap the whole error phrase into a quotation mark "Error comes in there" and paste that query into the search box.   The error might look like this  => Booting Puma => Rails 5.2.3 application starting in development => Run `rails server -h` for more startup options Exiting Traceback (most recent call last):         64: from bin/rails:3:in `