Problem getting auth type from Exchange server

[champlin2]

Describe the bug
Using exchangelib in some tests we have that were working previously. I believe the Exchange Server has been upgraded to 2019 CU14 since the last time the tests were run and now we are getting errors when trying to connect using basic authentication. From the debug log the error is "413 Request Entity Too Large"

Note this is running on Windows

To Reproduce
We get the error (see logs below) when running the following code:

credentials = Credentials(username=account, password=password)
config = Configuration(service_endpoint='/Exchange.asmx', credentials=credentials)
a = Account(primary_smtp_address=smtp_address, autodiscover = False, config=config, default_timezone=EWSTimeZone.from_timezone(pytz.timezone('UTC')))

Expected behavior
Be able to connect to Exchange accounts

Log output
Waiting for _protocol_cache_lock
Protocol call cache miss. Adding key '('https:///EWS/Exchange.asmx', Credentials('test.company.com\john', '********'))'
Waiting for _version_lock
Asking server for version info using API version Exchange2016
Processing chunk 1 containing 1 items
Calling service ConvertId
Trying API version Exchange2016
Server : Increasing session pool size from 0 to 1
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2016"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP2"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2016"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP2"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2016"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2015"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2013"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP2"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2010"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007_SP1"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large
Requesting b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2007"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>' from https:///EWS/Exchange.asmx
Trying to get service auth type for https:///EWS/Exchange.asmx
Unexpected response: 413 Request Entity Too Large

Additional context
Running exchangelib 5.4.0 and python 3.9.6

[champlin2]

Just realized that the Exchange server is using Kerberos for authentication so I tried to add 'auth_type=GSSAPI' to the Configuration object but I get an error stating:

'auth_type' 'gssapi' must be one of ['CBA', 'NTLM', 'OAuth 2.0', 'basic', 'digest', 'no authentication']

[ecederstrand]

You need to install exchangelib with Kerberos support for that to work. See https://ecederstrand.github.io/exchangelib/#installation and https://ecederstrand.github.io/exchangelib/#kerberos-and-sspi-authentication

[champlin2]

I installed the exchangelib[sspi] package and that got me further but now the response is 'Error server busy' even after restarting the Exchange server and there are no throttling policies in place:

Waiting for _protocol_cache_lock
Protocol call cache miss. Adding key '('https:///EWS/Exchange.asmx', Credentials('company.com\john', '********'))'
Waiting for _version_lock
Asking server for version info using API version Exchange2016
Processing chunk 1 containing 1 items
Calling service ConvertId
Trying API version Exchange2016
Server : Increasing session pool size from 0 to 1
Server : Created session 93035
Server : Waiting for session
Server : Got session 93035
Session 93035 thread 7100 timeout 120: POST'ing to https:///EWS/Exchange.asmx after 0s sleep
Timeout: 120
Session: 93035
Thread: 7100
Auth type: <requests_negotiate_sspi.requests_negotiate_sspi.HttpNegotiateAuth object at 0x09AE4C28>
URL: https:///EWS/Exchange.asmx
HTTP adapter: <exchangelib.protocol.NoVerifyHTTPAdapter object at 0x09AE4BB0>
Streaming: False
Response time: 0.030999999999039574
Status code: 413
Request headers: {'User-Agent': 'exchangelib/5.4.0 (python-requests/2.31.0)', 'Accept-Encoding': 'gzip, deflate', 'Accept': '/', 'Connection': 'Keep-Alive', 'Content-Type': 'text/xml; charset=utf-8', 'Content-Length': '481'}
Response headers: {'Server': 'Microsoft-IIS/10.0', 'X-Powered-By': 'ASP.NET', 'X-FEServer': 'exVM', 'Date': 'Wed, 15 May 2024 18:33:18 GMT', 'Connection': 'close', 'Content-Length': '0'}
Request XML: b'\n<s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/" xmlns:m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:t="http://schemas.microsoft.com/exchange/services/2006/types"><s:Header><t:RequestServerVersion Version="Exchange2016"/></s:Header><s:Body><m:ConvertId DestinationFormat="EntryId"><m:SourceIds><t:AlternateId Id="DUMMY" Format="EwsId" Mailbox="DUMMY"/></m:SourceIds></m:ConvertId></s:Body></s:Envelope>'
Response XML: b''
Server : Retiring session 93035
Server : Created session 49045
Server : Releasing session 49045
Got ErrorServerBusy (back off 10 seconds)

[ecederstrand]

If you want GSSAPI auth, you need to install exchangelib as pip install exchangelib[kerberos]

[champlin2]

I believe we want to use SSPI since the Exchange 2019 CU14 server has SChannel and Extended Protection enabled (as I'm told from the Exchange admin)

[ecederstrand]

Ok. There's not a lot to work with here. The server just returns an empty HTTP 413 response and closes the connection.

I would suggest working with your Exchange admin to find out why the connection fails. There may be hints in the Exchange server logs.

[champlin2]

Any idea what logs to look in for inbound connections? I noticed the error was 413 (Content Too Large)

[ecederstrand]

No idea, sorry. I'm not an Exchange admin myself.

[ecederstrand]

Closing because I don't think this is an issue with exchangelib itself. But please post the solution here if you find one, so others can benefit if they are having the same problem.

[champlin2]

@ecederstrand if I'm correct exchangelib uses the requests module to issue requests to the Exchange server correct? If so do you know if that uses the CURL library under the covers? We had to recompile the CURL library with the option to support the implementation of Secure Channel and Extended Protection in Exchange 2019 CU14 in one of our other products. We were getting the same 413 errors before doing this with the standard CURL library.

https://support.microsoft.com/en-us/topic/cumulative-update-14-for-exchange-server-2019-kb5035606-5d08ad6d-3527-41c9-82b6-e19d3ddf94db

https://learn.microsoft.com/en-us/exchange/plan-and-deploy/post-installation-tasks/security-best-practices/exchange-extended-protection?view=exchserver-2019

[ecederstrand]

requests does not use curl under the hood.

Installing exchangelib[sspi] will install the https://pypi.org/project/requests-negotiate-sspi/ package which adds SSPI auth for requests.

[champlin2]

@ecederstrand yes I have that installed but does that handle the Secure Channel changes in CU14?

[ecederstrand]

I don't know. You'll have to check with the authors of the requests-negotiate-sspi package.