Error: OAUTH2 SERVER LIBRARY Unavailable I have a website in drupal version 8.3.3 and since I installed oauth2 server module, I get the below error in Admin -> Reports -> Status Report

The OAuth2 server library is required for the OAuth2 module to function. Download the library using composer, downoad it from GitHub or use composer manager.

So I have added OAuth2 server library by running the below command 

$ git clone --branch master https://github.com/bshaffer/oauth2-server-php.git


This command executed successfully and also the files are created in libraries directory. But still I get the same error

Note: I followed the instruction from https://www.drupal.org/node/1938218
I encountered the same problem, being new to Drupal 8 development, and this project currently lacking documentation for its use with Drupal 8, probably because it is currently only available through a "dev" edition.

The solution I used was to add the two oauth2-server-php Composer dependencies in the "composer.json" file at the root of the Drupal folder, which are currently:

"require": {
    "bshaffer/oauth2-server-php": "~1.7",
    "bshaffer/oauth2-server-httpfoundation-bridge": "~1.1"
}


Then install them with Composer by executing "composer install". 

You can reach the project issue where I got help there: https://www.drupal.org/node/2897289#comment-12202222