Dear All, Here is my python code for testing REST API - import requests import json data = { "client_id": "52ba706f-902c-4208-b28d-c05df607f3c4", "client_secret": "de1c0400-ec02-4143-972e-752931968aed", "grant_type": "client_credentials", } headers = { 'Content_type': 'application/x-www-form-urlencoded' } response = requests.post("http://123.49.46.157:8080/api/v1/oauth/token", data=data, headers=headers) credentials = response.json() print(credentials) access_token = credentials['access_token'] print("Access_token: ",access_token) auth2 = { 'Authorization': 'Bearer' +access_token } response= requests.get("http://123.49.46.157:8080/api/v1/patrons", headers=auth2 ) print(response) When I run this code , I get access_token . Then I use this access token and try retrieve data. But getting authentication failure or response code 401 . My output below - (base) esharat@esharat-desktop:~/Desktop/Library$ python3 test.py {'access_token': 'MTY0NzM2MDQ3Mi00MzgwNzctMC42OTA2NTM5MzA1MDgxODQtM0pTSTcwdUhGcVdzaTlUUnhGcGVDaTFmaVg3Nm9v', 'expires_in': 3600, 'token_type': 'Bearer'} Access_token: MTY0NzM2MDQ3Mi00MzgwNzctMC42OTA2NTM5MzA1MDgxODQtM0pTSTcwdUhGcVdzaTlUUnhGcGVDaTFmaVg3Nm9v <Response [401]> Thanks in advance .