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Karl-WE avatar image
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Karl-WE asked Karl-WE commented

Exchange 2016 / Exchange 2019 wrong recommendations on Unified Communications Managed API

Today I noticed something very weird. The official docs still links UCMA as a prerequisite for EX2016 and EX2019 on-premises. The linked version 4.0 is not even supported for later .net versions in compliance with Exchange Compat matrix and UCMA 4.0 is not supported on Windows Server 2012 R2, Windows Server 2016 or Windows Server 2019.

The one that is supported is UCMA 6.0. Which is not mentioned in the docs or prerequisite checks.

A customer Exchange 2016 was stuck on downloading updates via sconfig at KB3175339 (Sec fix for UCMA 4.0) which is listed in catalog but the download is no longer available.

He is running Exchange Server 2016 CU 18 on Server 2016 LTSC. CU 18 or previous CUs never mentioned to check for the outdated version of UCMA 4.0, nor did Microsoft update them.

Installing UCMA 6.0 was not an easy task though. Even when all named prerequisites are met the installer will quit after specifying the install path.
Reason was found in the installer logs.
The UCMA Setup tries to Install C++ Redist 2015-2019 x64 package version 14.12.x which is heavily outdated. Unfortunately the one that did the package for UCMA did a wrong hardcoded version check.

So it required me uninstall UCMA 4.0 that's ok.

But it also required me to uninstall C++ Redist 2015-2019 x64
I would like to recommend anyone involved with packaging / assembling installers: never do hardcode version checks with version equal % but with equal or higher %, please.
The current and secure version is C++ 2015-2019 Version 14.28.x


2 Questions:
why no one care to update the docs for UCMA 6.0 and actually reading the requirements on the download page
why no one cared to update UCMA with Exchange CUs while it is a prereq for Exchange?

UCMA 4.0 requirements
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UCMA 5.0 requirements
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UCMA 6.0 requirements
40941-image.png



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BodisHS avatar image
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BodisHS answered

Any news on this @Karl-WE ?
Seems to me that Microsoft did not even take a look at this so far.

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BodisHS avatar image
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BodisHS answered

Just spoke to Christian from Microsoft support which suggested me to install C++ 2008, since that the best and only solution for this issue.
I have absolutely no clue why they would even consider saying anything like this.

Will try it once more tommorow to see if I can talk to someone else on this matter.

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BodisHS avatar image
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BodisHS answered

Sorry for all the messages.
Got a reply on the GitHub of the HealthCheck script of last week Exchange vulnerabilities.
They (Microsoft) will check internally with their Exchange team.

https://github.com/dpaulson45/HealthChecker/issues/538

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Karl-WE avatar image
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Karl-WE answered

C++ 2008 is officially out of support
no need to be sorry. I am still waiting for a response from MSFT.

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Karl-WE avatar image
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Karl-WE answered

as the project has moved to a different repository the PR is now here
https://github.com/microsoft/CSS-Exchange/issues/535

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Karl-WE avatar image
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Karl-WE answered

Good news. The UCMA topic has been approved. UCMA 4.0 is not supported in 2016 and 2019, seems like a leftover from Exchange 2010/2013 docs.

https://github.com/MicrosoftDocs/OfficeDocs-Exchange/pull/2771#event-5280924630

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Karl-WE avatar image
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Karl-WE answered Karl-WE edited
  • Backup Exchange

  • Uninstall UCMA 4.0

  • Uninstall any C++ redists 2015-2019 due to a bug in the setup of UCMA 6.0

  • reboot

  • Download UCMA 6.0, install it

  • Care to Update C++ Redists 2015-2019 from C++ latest Redist page (and keep these updated), no WU, WuFB do not care for this.

Caveat: Health Checker will not yet cause a green flag until said PR is not merged into a new build of the healthchecker.
you cannot have UCMA 4.0 or 5.0 or 6.0 side by side. It could be some docs are still not updated like: https://docs.microsoft.com//exchange/plan-and-deploy/deployment-ref/ms-exch-setupreadiness-ucmaredistmsi?view=exchserver-2019&source=docs



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thiagobeier avatar image
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thiagobeier answered Karl-WE commented

tried the fix and it didn't work
removed all UCMA 4.0 and 5.0 from OS (2016 STD 10.0.14393 N/A Build 14393) full patched
exchange 2016 CU22
services broken
- Microsoft Exchange Unified Messaging Call Router
- Microsoft Exchange Unified Messaging
tmp files at c:\windows\temp

701828, TID:8 (0) : UMServiceBase failed to start
701828, TID:8 (0) : Unhandled Exception Received, Sending Watson Report. Exception = System.IO.FileNotFoundException: Could not load file or assembly 'Microsoft.Rtc.Collaboration, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified.
File name: 'Microsoft.Rtc.Collaboration, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35'
at Microsoft.Exchange.UM.UMService.UMConnectionManagerHelper.TLSConnectionManager.Initialize()

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Hi Thiagobeier,
if you run into problems, I am afraid you have to keep UCMA 4.0. The Exchange Team declined my pull request to update the Health Checker and later revoked the update of docs.microsoft.com as they won't solve this dilemma due technical dependencies.

Docs now has a new disclaimer tho, that UCMA 4.0 is still needed even though it is outdated.
Seeing the Exchange Server roadmap, the end of Exchange On-premises, at least 2016 / 2019 is near.

In future you have to step up to a subscription model for on-premises Exchange or migrate to cloud.

References:
https://github.com/microsoft/CSS-Exchange/issues/535
https://github.com/MicrosoftDocs/OfficeDocs-Exchange/pull/2771#issuecomment-917013845

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