If we get error as Auth private key does not exist on the browser when we run any laravel project .

Something similar to

Then we just need to install the passport and do the changes to the places where needed.

Command to install Passport:

php artisan passport:install

Soon after the passport is install we will get the following things:

1. Client id
2. Client secret

We need to put client id in the in env files where required.

Somewhat similar to given below:

We need to change the client id and client secret to all the places where the concern configuration are used.

Few important links for reference :

1. Setup laravel project and understand folder structure click here.
2. Crud operation and detailed explaination. click here.