Hello Microsoft community,

I am encountering an issue while trying to run Outlook desktop on one computer. An error indicates problems connecting to Exchange online. So, i checked connection to Exchange Online (EXO) using the Microsoft Remote Connectivity Analyzer. The error message and details are as follows:

...

Test: Check Name operation for the user <user's e-mail> on the server outlook.office365.com.

An error occurred while attempting to resolve the name.

Additional information:

A protocol layer error occurred. HttpStatusCode: 500

Failure LID: 47372

Failure information:

REQUEST [2023-06-20T12:47:03.1276851Z] [ResolvedIPs: 52.96.24.210,52.96.69.98,52.96.214.50,40.99.226.130]

POST /mapi/nspi/?mailboxId=<id with domain> HTTP/1.1

...

X-ClientApplication: MapiHttpClient/15.20.5791.1

X-RequestType: Bind

Host: outlook.office365.com

Content-Length: 45

--- REQUEST BODY [+0.009] ---

..[BODY SIZE: 45]

--- REQUEST SENT [+0.009] ---

RESPONSE [+0.491]

HTTP/1.1 500

Transfer-Encoding: chunked

request-id: b6212bf2-4a5b-b763-9943-bdbb6a02200e

Alt-Svc: h3=":443",h3-29=":443"

X-CalculatedBETarget: PA4PR03MB8197.eurprd03.PROD.OUTLOOK.COM

X-BackEndHttpStatus: 500

X-DiagInfo: PA4PR03MB8197

X-BEServer: PA4PR03MB8197

X-Proxy-RoutingCorrectness: 1

X-FailureContext: BackEnd;500;;;;;

X-Proxy-BackendServerStatus: 500

X-FirstHopCafeEFZ: DSM

X-FEProxyInfo: DS7PR03CA0102.NAMPRD03.PROD.OUTLOOK.COM

X-FEEFZInfo: DSM

X-FEServer: DS7PR03CA0102

Cache-Control: private

Content-Type: text/html; charset=utf-8

Date: Tue, 20 Jun 2023 12:47:03 GMT

Server: Microsoft-IIS/10.0

X-AspNet-Version: 4.0.30319

X-Powered-By: ASP.NET

...

I would appreciate any assistance or insights regarding this issue. There is a protocol layer error with HttpStatusCode 500. I have already verified user's credentials, but the connection is still not successful. is this a problem with PA4PR03MB8197.eurprd03.PROD.OUTLOOK.COM endpoint?

The user can successfully use OWA and Outlook installed on another computer,

We have hybrid, user uses Prof plus 2019 and connection is MAPI.

Thank you in advance for your support.

Best regards,

Wojtek