Delete the my app folder and redo
rails new myapp -d postgresql
After just add the lines in config/database.yml
But don't modify anything else and respect the indentation
Last do
rails db:create

PostgreSQL. Versions 9.1 and up are supported.

Install the pg driver:

gem install pg

On OS X with Homebrew:

gem install pg -- --with-pg-config=/usr/local/bin/pg_config

On OS X with MacPorts:

gem install pg -- --with-pg-config=/opt/local/lib/postgresql84/bin/pg_config

On Windows:

gem install pg

Choose the win32 build.

Install PostgreSQL and put its /bin directory on your path.

Configure Using Gemfile

gem 'pg'

default: &default
host: localhost
adapter: postgresql
encoding: unicode
username: postgres
password:
# For details on connection pooling, see Rails configuration guide
# http://guides.rubyonrails.org/configuring.html#database-pooling
pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

development:
<<: *default
database: myapp_development

# The specified database role being used to connect to postgres.
# To create additional roles in postgres see $ createuser --help.
# When left blank, postgres will use the default role. This is
# the same name as the operating system user that initialized the database.
#username: myapp

# The password associated with the postgres role (username).
#password:

# Connect on a TCP socket. Omitted by default since the client uses a
# domain socket that doesn't need configuration. Windows does not have
# domain sockets, so uncomment these lines.
#host: localhost

# The TCP port the server listens on. Defaults to 5432.
# If your server runs on a different port number, change accordingly.
#port: 5432

# Schema search path. The server defaults to $user,public
#schema_search_path: myapp,sharedapp,public

# Minimum log levels, in increasing order:
# debug5, debug4, debug3, debug2, debug1,
# log, notice, warning, error, fatal, and panic
# Defaults to warning.
#min_messages: notice

Warning: The database defined as "test" will be erased and

re-generated from your development database when you run "rake".

Do not set this db to the same as development or production.

test:
<<: *default
database: myapp_test

As with config/secrets.yml, you never want to store sensitive information,

like your database password, in your source code. If your source code is

ever seen by anyone, they now have access to your database.

Instead, provide the password as a unix environment variable when you boot

the app. Read http://guides.rubyonrails.org/configuring.html#configuring-a-database

for a full rundown on how to provide these environment variables in a

production deployment.

On Heroku and other platform providers, you may have a full connection URL

available as an environment variable. For example:

DATABASE_URL="postgres://myuser:mypass@localhost/somedatabase"

You can use this database configuration with:

production:

url: <%= ENV['DATABASE_URL'] %>

production:
<<: *default
database: myapp_production
username: myapp
password: <%= ENV['APMANAGER_DATABASE_PASSWORD'] %>

just add your password

Can you paste all the database.yml file here I will correct it for you

Can you paste exactly what you added in the config/database.yml?

it should be exactly like this:
default: &default
host: localhost
adapter: postgresql
encoding: unicode
username: postgres
password: Password123

instead of Password123 put your password

yes add the lines
host: localhost
username: postgres
`password: your password #here put your password from the Postgresql install

You need to add the database credentials
open your editor (eg, Atom, Visual Code ... ) in the myapp app folder, go to config/database.yml find this lines
default: &default
host: localhost #add this line
adapter: postgresql
encoding: unicode
username: postgres #add this line
password: "put your password from the Postgresql install" #add this line
and then do:
rails db:create
in your terminal

Did the:
rails new myapp -d postgresql command worked?

Hi Zainab, first in file explorer go to C:/ and delete myapp folder.
Then open terminal or cmd what whever you use for WSL and paste this command:
sudo umount /mnt/c sudo mount -t drvfs C: /mnt/c -o metadata
After try again:
rails new myapp -d postgresql
It should work

I’ve got identical issue following from that guide on Win10 WSL.

And i found this issue may be solved with Chmod/Chown WSL Improvements
https://devblogs.microsoft.com/commandline/chmod-chown-wsl-improvements/ 32

Use
sudo umount /mnt/c sudo mount -t drvfs C: /mnt/c -o metadata
to change /mnt/c setting and it works for me

*You must delete files from incomplete rails new command first

Hi Chris,
when I do 'cd'=> and after 'pwd' => home/user_name,
therefore should i change the commands from:
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
exec $SHELL
to:
echo 'export PATH="$HOME/user_name/.rbenv/bin:$PATH"' >> ~/.bashrc
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
exec $SHELL
???

this solved my issue:
add this to the win 10 path variable:
C:\Users\”Your user” \AppData\Local\Packages\CanonicalGroupLimited.UbuntuonWindows_79rhkp1fndgsc\LocalState\rootfs\mnt

i have the same problem:
i tried an older version of bundler still no change.
then i've seen this :
gem install bundler -v 2.0.1
Fetching: bundler-2.0.1.gem (100%)
/home/cod/.rbenv/rbenv.d/exec/gem-rehash/rubygems_plugin.rb:6: warning: Insecure world writable dir /home/cod/.rbenv/versions/2.5.7 in PATH, mode 040777
Successfully installed bundler-2.0.1
Parsing documentation for bundler-2.0.1
Installing ri documentation for bundler-2.0.1
Done installing documentation for bundler after 5 seconds
1 gem installed

so i think that your solution chmod +t -R ~/.bundle is not good in my case,
error
chmod: cannot access '/home/cod/.bundle': No such file or directory

any idea for an work around?
thank you