Problem with port when launching ruby/rails app on windows10/ubuntu - ruby-on-rails

Question

I have two different projects - one that I made for practicing purpose and one that is a real project.
I'm using RVM to set version and they both run on 2.6.0 & rails 5.2.3
My practice project launches fine on localhost:3000. However I can't see anywhere or anyhow that it's being used while running the app (checking in resource manager/netstat)
However when I'm trying to launch the second app I'm getting "listen: Address already in use - listen(2) and rails shuts down.
I've tried restarting the terminal/my computer just to make sure nothing is running on port 3000 and I can't for the life of me understand why it's not working.
Has anyone experienced something similar? I've obviously tried looking at similar questions here however most answers are related to terminating whatever is running on 3000 at the moment, but I can't confirm that anything is.
UPDATED:
Ok so when I launch the app that complains about port being in use I get the following:
/usr/share/rvm/rubies/ruby-2.6.0/bin/ruby: warning: shebang line ending with \r may cause problems
After that it tries to start, it says it's listening on tcp://127.0.0.1:3000 which is fine and dandy, but then it stops and here's the trace:
Traceback (most recent call last):
19: from bin/rails:4:in `<main>'
18: from bin/rails:4:in `require'
17: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/commands.rb:18:in `<top (required)>'
16: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/command.rb:46:in `invoke'
15: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/command/base.rb:65:in `perform'
14: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
13: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
12: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
11: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `perform'
10: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:142:in `tap'
9: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:147:in `block in perform'
8: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/railties-5.2.3/lib/rails/commands/server/server_command.rb:53:in `start'
7: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/rack-2.0.7/lib/rack/server.rb:297:in `start'
6: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/rack/handler/puma.rb:73:in `run'
5: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/puma/launcher.rb:172:in `run'
4: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/puma/cluster.rb:463:in `run'
3: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/puma/runner.rb:82:in `start_control'
2: from /usr/share/rvm/rubies/ruby-2.6.0/lib/ruby/2.6.0/forwardable.rb:230:in `add_unix_listener'
1: from /home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/puma/binder.rb:328:in `add_unix_listener'
/home/sorgmantel/.rvm/gems/ruby-2.6.0/gems/puma-4.3.0/lib/puma/binder.rb:328:in `listen': Address already in use - listen(2) (Errno::EADDRINUSE)
Breadcrumb Mongo query succeeded meta_data collection:Array has been dropped for having an invalid data type
Is it possible that it has to do with file origins? My project runs fine because it's written in windows but I can't run the other one that was written on MAC, with the different line endings and all. I've heard Ruby can be sensitive when you run it on windows machines.

Answer 1

So apparantly this was caused by
activate_control_app
in my puma.rb file. When I commented it out the app launched fine.