AADSTS53003: Access has been blocked by Conditional Access policies. The access policy does not allow token issuance.

Explanation of the problem

When attempting to access SharePoint, an error occurred with the following message: “An error occurred while retrieving token from XML response: AADSTS53003: Access has been blocked by Conditional Access policies. The access policy does not allow token issuance.” This error indicates that a conditional access policy is blocking token issuance, preventing access to SharePoint.

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Problem solution for AADSTS53003: Access has been blocked by Conditional Access policies. The access policy does not allow token issuance.

const accessToken = 'your_access_token';

fetch('https://graph.microsoft.com/v1.0/sites/root', {
  headers: {
    Authorization: `Bearer ${accessToken}`,
  },
})
  .then(response => {
    console.log('Response status:', response.status);
    return response.json();
  })
  .then(data => {
    console.log('Site name:', data.name);
  })
  .catch(error => {
    console.error('Error accessing SharePoint:', error);
  });

Problem: authentication

One common problem with the Office365-REST-Python-Client is related to authentication. Users might encounter authentication issues when trying to access a SharePoint site or an Outlook mailbox. The client requires a valid access token for authentication, which is generated using the OAuth2 authentication protocol. If the user is not authorized to access the resource or if the token is expired or invalid, the client raises an authentication error.

Solution:

To solve this problem, the user needs to check if the credentials used for authentication are valid and that the access token has not expired. Users can use the OAuth2Session class in the requests_oauthlib library to get an access token or refresh it if it has expired.

Problem: structure of the REST API requests

Users might face errors when sending requests that are not properly formatted, contain incorrect parameters or are not supported by the API. For instance, a user might get a “404 Not Found” error when trying to access a resource that does not exist.

Solution:

To solve this problem, the user needs to ensure that the REST API request is correctly formatted and that the correct parameters are used. Users can consult the Microsoft Graph API documentation for the correct format and parameters for the request. The client also provides a Response object that contains the response body, status code, and headers for each request. Users can use this object to debug the request and get more information about the error.

Problem: performance

Users might face slow response times when sending REST API requests to a SharePoint site or an Outlook mailbox. This could be due to various factors, such as network latency, server load, or inefficient code.

Solution:

from office365.runtime.auth.authentication_context import AuthenticationContext
from office365.sharepoint.client_context import ClientContext

url = "https://your-organization.sharepoint.com"
username = "username@your-organization.com"
password = "your-password"

ctx_auth = AuthenticationContext(url)
if ctx_auth.acquire_token_for_user(username, password):
    ctx = ClientContext(url, ctx_auth)
    web = ctx.web
    ctx.load(web)
    ctx.execute_query()
    print("Web title: {0}".format(web.properties['Title']))
else:
    print(ctx_auth.get_last_error())