ExchangeImpersonation SOAP header must be present for this type of OAuth token in Python

Recently Microsoft has withdrawn the basic authentication service for accessing the Exchange Service. Therefore I am working on switching the authentication from basic to OAuth based. However, during the testing, I come across the below exception.

  File "/usr/local/lib/python3.6/site-packages/exchangelib/services/common.py", line 423, in _raise_soap_errors
    raise vars(errors)[code](msg)
exchangelib.errors.ErrorInvalidExchangeImpersonationHeaderData: ExchangeImpersonation SOAP header must be present for this type of OAuth token.

I went through the suggestions mentioned here https://github.com/ecederstrand/exchangelib/issues/735 for solving but had no luck solving the issues.

#Implementation

redentials = OAuth2Credentials(
            client_id=self.client_id, client_secret=self.client_secret, tenant_id=self.tenant_id,
            identity=Identity(smtp_address=self.email_address)
        )
        log.info(f"Credentials ==>{credentials}")
        config = Configuration(server=self.email_server, credentials=credentials,  auth_type=OAUTH2,  version=Version(build=EXCHANGE_O365))
        self.account = Account(self.email_address, access_type=DELEGATE, config=config)

Any suggestion on solving the above exception would be a great help. Thanks in Advance

Answer

When your using the client_credentials flow you need to use impersonation in EWS eg change

access_type=DELEGATE

to

access_type=IMPERSONATION

You also need to make sure you Application registration has the full_access_as_app permission and its consented to see https://learn.microsoft.com/en-us/exchange/client-developer/exchange-web-services/how-to-authenticate-an-ews-application-by-using-oauth