This browser is no longer supported.
Upgrade to Microsoft Edge to take advantage of the latest features, security updates, and technical support.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(3.2, 0%, 10%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMA%3C/text%3E%3C/svg%3E)
Hi,
I'm in the process of configuring OAuth from en on-premises Exchange 2016 CU19+ install to in order to have calendar integration within Microsoft Teams.
The HCW wizard has completed successfully, but no calender tab is visible within the Teams client (thick or web - same issue).
I've tested with
Test-OAuthConnectivity -Service EWS -TargetUri https://outlook.office365.com/ews/exchange.asmx -Mailbox mailbox@localdomain.tld
And the error is
AADSTS700027: Client assertion contains an invalid signature. [Reason - The key was not found., Thumbprint of key used by client: xxxxxxxxx
I've tried verifying the certificate used for OAuth and it looks OK.
Running this command I've saved the certificate and compared it to the thumbprint from get-authConfig - they match and have not expired
Get-MsolServicePrincipalCredential -ServicePrincipalName "00000002-0000-0ff1-ce00-000000000000" -ReturnKeyValues $true
I'm kind of stumped as to how to solve this issue.
Thank you all for your suggestions - I've gotten a bit further
Unfortunately the issue with the Teams client persists, and I've opened a case with Microsoft - I'll make sure to update this thread once it has been resolved. It may help others facing the same issue.
/mikkel
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(28.799999999999997, 82%, 12%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EEY%3C/text%3E%3C/svg%3E)
Hi,
Any updates till now?
Thanks in advance for your information.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(57.599999999999994, 95%, 15%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EMA%3C/text%3E%3C/svg%3E)
Unfortunately not as of yet.
Working with o365 support on it, but so for I've just run various scripts to verify the oncfiguration. They did ask me to update to the very latest CU (from March 16th) - I've asked for clarification on that as CU19 should be fully supported still, and we are not in the habit of installing CU so soon after publication.
/mikkel
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(204.8, 78%, 29%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EGR%3C/text%3E%3C/svg%3E)
Were you able to resolve this issue? We had no issues with the calendar not showing with our users, but recently we have started to have this problem. Some work and some dont. All new users have this issue and we cannot seem to figure out why this is happening.
Hi,
Yes the issue has been resolved. It was due to a legacy Exchange 2010 install still present. With the Ex2010 present the HCW does not do the OAuth part, and I most have done it incorrectly when doing it manually.
I got the go ahead to remove the Ex2010 from the organisation and upon re-running the HCW it started working,
In your case I would imagine that doesn't sound like what's happening. Have you tried running the "Teams calendar tester" from https://testconnectivity.microsoft.com/tests/TeamsCalendarMissing/input
In my case the mailbox was listed as "undiscoverable" - which honestly didn't help me at all. In your case it would make sense to test a working and a non-working mailbox and try to see what might be different.
/mikkel
When running the test, we get the same error, but it does this for an account that is working and an account that is not. We do not have any mailboxes in O365, everything is still on-prem. We also get the same undiscoverable message, so trying to figure out what is going on. I also re-ran the HCW just in case, but that still does not seem to help. I do have a case open with MS support, so hopefully we can figure out what is going on.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(166.4, 1%, 26%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EPO%3C/text%3E%3C/svg%3E)
Were you able to fix issue?