Mac Teams client not able to connect to Calendar - Exchange On-Premise

Mike Prager 1

Hi,

We have Exchange On-Premise and 6 employees on Windows and one on Mac OS. We have been using Teams with no issues for years. Recently, the Mac user cannot connect to their calendar in Teams. All the Windows users have no issues. When I run the remote Connectivity Analyzer on their machine, it fails at "Verifying if the users mailbox is discoverable by the Teams Service" and I get this.

The user's mailbox is not discoverable by the Teams service. Please ask your administrators to verify the user has a mailbox and to confirm the connectivity between Teams and Exchange. Error Message: Could not fetch user exchange mailbox endpoint using AutoDV2. Error details: Failed to execute AutoDiscover request. Exception: Unexpected character encountered while parsing value: <. Path '', line 0, position 0.Unexpected character encountered while parsing value: <. Path '', line 0, position 0.

If I try this on my machine with his credentials, it works fine.

On his machine, If I browse to https://fqdn/EWS/Exchange.asmx I can enter his credentials and get back the "Service" page which I originally thought was the issue.

I have looked at the IIS logs on Exchange and and event log but I can't see anything that would indicate any issue.

Any ideas as I've run out of them?

Thanks in advance

Mike

1 answer

Jake Zhang-MSFT 8,010 Reputation points Microsoft Vendor

2025-01-07T02:02:04.27+00:00
Hi @Mike Prager ,

Welcome to the Microsoft Q&A platform!

Based on your problem description, you can try the following steps to resolve the issue:

Make sure the Autodiscover service is correctly configured and accessible from your Mac. The error message indicates that there is a problem parsing the Autodiscover response, which may be caused by incorrect configuration or malformed response format.

On your Mac, try clearing the Teams cache. You can do this by exiting Teams and then deleting the contents of the following folders:

~/Library/Application Support/Microsoft/Teams

~/Library/Caches/com.microsoft.teams

~/Library/Cookies/com.microsoft.teams.binarycookies

~/Library/Preferences/com.microsoft.teams.plist

Verify that the DNS settings on your Mac correctly resolve the AutoDiscover service. Incorrect DNS settings can cause service discovery issues.

Make sure there are no firewall or proxy settings on your Mac that may block AutoDiscover requests.

As a temporary workaround, you can try manually configuring the Exchange Web Services (EWS) URL in Teams. This can sometimes bypass AutoDiscover issues.

If you are in a hybrid Exchange environment, ensure that the hybrid configuration is set up correctly and that OAuth authentication is configured correctly.

If these steps do not resolve the issue, it may be helpful to capture the network traffic on the Mac using a tool such as Wireshark to see if there are any anomalies in the AutoDiscover response.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang
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Mike Prager 1 Reputation point

2025-01-07T09:34:53.8333333+00:00

Hi Jake,

Thanks for your reply.

How do I test No.5 - I can't see where I'd set the EWS URL for Teams?

If there was an issue with the AutoDiscover service, wouldn't everyone have the same issue?

I'll test the other ones

Thanks

Mike

Mike Prager 1 Reputation point

2025-01-07T13:23:54.1133333+00:00

Hi Jake,

Clearing the cache made no difference.

It's only this 1 user from a mac that is having the issues so things must be setup correctly if 6 out of 7 if us are working fine.

He can get to OWA with no issues from his machine so I know that IIS / Authentication for his account is working.

Can you let me know how I hard code the EWS Url and I'll test that

Thanks

Mike

Mike Prager 1 Reputation point

2025-01-07T15:32:41.6433333+00:00

Hi Jake,

I have some more information but not sure what is causing it. I used the MS Remote Connectivity Analyzer to test the Teams Exchange Integration. At the bit where it does, "Testing the Microsoft 365 Autodiscover V2 service", it pings off a request to

https://outlook.office365.com/autodiscover/autodiscover.json?Email=myuser@tripartum.com&Protocol=EWS

However, what comes back from this is not our exchange server/EWS address but the address of our hosting providers AutoDiscover url.

On the Teams / Exchange test, when trying to retrieve the userPropertiesSettings, on his call on the Mac, it says mailboxDiscoverable: undiscoverable whereas my call returns the ewsUrl (although I also get could not fetch user exchange mailbox endpoint using AutoDV2) - however mine works as I assume it has the ewsUrl so can work.

So the question is why is his call failing and does it have anything to do with the Autodiscover from O365?

Any ideas?

Thanks

Mike

Jake Zhang-MSFT 8,010 Reputation points Microsoft Vendor

2025-01-08T05:22:58.6166667+00:00

Hi @Mike Prager ,

Thanks for your response. Let's address your points one by one:

Unfortunately, Microsoft Teams does not provide a direct way to manually set the EWS URL within the application itself. However, you can configure the EWS URL in the Exchange settings. This is typically done through the Exchange Management Shell or the Exchange Admin Center. Here’s a general approach using PowerShell:

Set-WebServicesVirtualDirectory -Identity "YourServer\EWS (Default Web Site)" -ExternalUrl https://yourdomain.com/EWS/Exchange.asmx

This command sets the external URL for the EWS virtual directory. Make sure to replace YourServer and yourdomain.com with your actual server name and domain.

You’re correct that if there was a widespread issue with the AutoDiscover service, it would likely affect all users. Since it’s only affecting one user on a Mac, it suggests a more localized issue.

Since clearing the cache didn’t help, we can rule that out as the cause.

The fact that the user can access OWA without issues indicates that the basic IIS and authentication settings are correct.

The information you provided about the AutoDiscover request returning the hosting provider’s URL instead of your Exchange server’s URL is crucial. This suggests that the AutoDiscover service might be misconfigured or that there’s an issue with DNS settings.

Ensure that the DNS settings for your domain are correctly pointing to your on-premises Exchange server for AutoDiscover. You might need to create or update the DNS SRV record for AutoDiscover.

Verify the AutoDiscover configuration on your Exchange server. You can use the following PowerShell command to check the AutoDiscover settings:

Get-ClientAccessService | FL AutoDiscoverServiceInternalUri

As a temporary workaround, you can add an entry to the Mac’s hosts file to point the AutoDiscover URL directly to your Exchange server’s IP address. This can help bypass any DNS issues.

Since the issue is isolated to one user on a Mac, capturing network traffic using a tool like Wireshark might reveal more details about what’s happening during the AutoDiscover process.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang

Mike Prager 1 Reputation point

2025-01-08T11:33:49.8466667+00:00

Hi Jake,

It turned out to be the SRV record for Autodiscover was set to our DNS hosting provider and not our Exchange server. I don't quite know why the windows clients all worked unless they went straight to the Autodiscover A record (which was correct) but it seems like the Mac client does do query on the service record and this was incorrect.

Thanks for your help

Mike

Jake Zhang-MSFT 8,010 Reputation points Microsoft Vendor

2025-01-10T09:18:45.1233333+00:00

Hi @Mike Prager ,

I'm glad you found the root cause! It's interesting how the Mac client behaves differently with the SRV record. It makes sense that the Windows clients might have been using the A record directly, bypassing the incorrect SRV record.

Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang
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Mac Teams client not able to connect to Calendar - Exchange On-Premise

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