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Exchange Server 2016 · Release Health

Known issues in Exchange Server 2016

Problems Microsoft has confirmed for this version, from its official release health notes. 11 still open or mitigated.

Exchange Server: SE 2019 2016
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Active known issues

Open & Mitigated
11 active issues
  1. Open Exchange Server 2016 2019 SE Affects: Organizations and IT administrators Started with KB5121573 · Aug 11, 2026

    Published calendar (.ics) returns HTTP 500 for calendar applications

    After KB5121573, subscriptions to anonymously published Exchange calendars might stop refreshing. Calendar apps might receive an HTTP 500 error.

    How to apply the workaround IIS / URL Rewrite

    Add a URL Rewrite rule to the Exchange Back End site. It adds layout=premium to calendar-feed requests that do not already have a layout parameter.

    Step-by-step workaround instructions
    5 steps
    Show steps Hide steps
    Step-by-step procedure
    1. Confirm that the IIS URL Rewrite module is installed.
    2. In IIS Manager, add a blank inbound rule to the Exchange Back End site's URL Rewrite settings.
    3. Match ^owa/calendar/.+\.ics$ and add a condition that excludes requests whose query string already contains layout=.
    4. Rewrite the URL to {R:0}?layout=premium&{QUERY_STRING}; clear Append query string.
    5. Apply the rule on every server that serves the published calendar. No application pool recycle is required.
  2. Open Exchange Server 2016 2019 SE Affects: Organizations and IT administrators Started with KB5103212 · Jul 14, 2026

    Wrapper messages appear in shared mailbox in hybrid environments after installing the June 2026 Security Update

    In Exchange hybrid, sent messages might appear as attachments in an Exchange Online shared mailbox Inbox. With an on-premises sender, Send As or Send on Behalf rights, and message-copy enabled, this occurs; KB5121608 resolves it.

    How to apply the workaround Exchange Management Shell

    The article says to remove the override if it was created as a workaround for this issue.

    Step-by-step instructions, command & download kit
    2 steps Exchange Management Shell Instructions (.txt)
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    Step-by-step procedure
    1. In Exchange Management Shell, check whether the override exists.
    2. If it exists, remove it.
    Exchange Management Shell 
    > Get-SettingOverride "DisableBlockSharedAndUserMailboxHeaders"> Remove-SettingOverride "DisableBlockSharedAndUserMailboxHeaders"
  3. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5049233 · Nov 27, 2024

    A file version error occurs when you try to install Exchange Server November 2024 SU

    Installing the November 2024 security update might fail with a file version error. If the first workaround does not help, the article provides a second method.

    How to apply the workaround Workaround

    Restart the server, check Exchange service startup types and .NET Framework 4.8, then retry the installation. If Exchange services are disabled, restore their startup configuration first.

    Step-by-step instructions, command & download kit
    5 steps powershell.exe · Administrator Instructions (.txt)
    Show steps & kit Hide steps & kit
    Step-by-step procedure
    1. Restart the Exchange server.
    2. Check the Exchange services with the listed Get-Service command.
    3. If their StartType is Disabled, run the setup commands to restore the services, then check their status again.
    4. Check for the .NET Framework 4.8 update with Get-Hotfix. If it is missing, install it through Windows Update.
    5. Retry the November 2024 security update installation. If this method does not help, follow Workaround 2 in the linked article.
    powershell.exe · Administrator 
    > Get-Service -DisplayName "Microsoft exchange*" | ft DisplayName,Starttype ,Status> cd "C:\Program Files\Microsoft\Exchange Server\V15\Bin"> Add-PSSnapin -Name Microsoft.Exchange.Management.PowerShell.Setup -ErrorAction SilentlyContinue> .\ServiceControl.ps1 AfterPatch> Get-Hotfix
  4. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5049233 · Nov 27, 2024

    The Edge Transport service stops responding after installing November 2024 SU

    The Edge Transport service might stop responding and restart after this security update when it decrypts certain externally protected messages. The issue is resolved by the May 29, 2025 hotfix for the applicable Exchange version.

    How to apply the workaround Exchange Management Shell

    MSIPC is enabled by default in the November 2024 security update. Disabling it works around the service failure described in the issue.

    Step-by-step instructions, command & download kit
    2 steps Exchange Management Shell Instructions (.txt)
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    Step-by-step procedure
    1. In an elevated Exchange Management Shell window, run the commands in order.
    2. After installing the applicable May 29, 2025 hotfix, remove the setting override and refresh configuration as shown in the undo commands.
    Exchange Management Shell 
    > New-SettingOverride –Name "DisableMSIPC" -Component Encryption –Section UseMSIPC –Parameters @("Enabled=false") -Reason "Disabling MSIPC stack"> Get-ExchangeDiagnosticInfo -Process Microsoft.Exchange.Directory.TopologyService -Component VariantConfiguration -Argument Refresh> Restart-Service MSExchangeTransport
  5. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5049233 · Nov 27, 2024

    A time zone exception occurs after installing Exchange Server November 2024 SU (Version 1 or Version 2)

    After either version of the November 2024 security update, calendar files might not preview or add to calendars. The issue can also affect processing of messages with calendar attachments.

    How to apply the workaround Workaround

    The mapping file has a duplicate entry for Asia/Bishkek. Removing one copy works around the resulting time zone exception.

    Step-by-step instructions, command & download kit
    4 steps powershell.exe · Administrator Instructions (.txt)
    Show steps & kit Hide steps & kit
    Step-by-step procedure
    1. Back up IanaTimeZoneMappings.xml in the Exchange V15\Bin folder.
    2. Open the file and find the two copies of <Map IANA="Asia/Bishkek" Win="Central Asia Standard Time" />.
    3. Delete one copy and save the file.
    4. In an elevated PowerShell window, restart the web and transport services.
    powershell.exe · Administrator 
    > Restart-Service -Name W3SVC, WAS -Force> Restart-Service -Name MSExchangeTransport
  6. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5044062 · Nov 12, 2024

    Exchange Transport Rules and Data Loss Prevention rules don't work after installing November 2024 SU V1

    After November 2024 SU V1, Exchange might stop processing Transport Rules and DLP rules. The issue is listed for this update.

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Defer KB5044062 on affected systems until a fix is released.

  7. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5036386 · Mar 12, 2024

    After you install this SU, you can't preview Microsoft Word documents in Outlook on the web (OWA), and you receive an error message

    Word documents cannot be previewed in OWA, and an error appears. KB5037224 fixes this.

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Defer KB5036386 on affected systems until a fix is released.

  8. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5036386 · Mar 12, 2024

    After you install this SU, you receive a "We're having trouble fetching results from the server" error message when you run a search in Microsoft Outlook cached mode

    Outlook cached-mode searches show a “We're having trouble fetching results from the server” error. Searches work in online mode or OWA. KB5037224 fixes this.

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Defer KB5036386 on affected systems until a fix is released.

  9. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5036386 · Mar 12, 2024

    After you install this SU, OwaDeepTestProbe and EacBackEndLogonProbe are no longer working

    OwaDeepTestProbe and EacBackEndLogonProbe fail after installation, and their monitors show Unhealthy. KB5037224 fixes this.

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Defer KB5036386 on affected systems until a fix is released.

  10. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5036386 · Mar 12, 2024

    After you install this SU, Download Domains are no longer working as expected

    Users of some Outlook versions can no longer see inline images in OWA or download attachments through OWA. KB5037224 fixes this.

    Workaround status No workaround yet

    Microsoft has not published a manual workaround for this issue yet. Defer KB5036386 on affected systems until a fix is released.

  11. Open Exchange Server 2016 2019 Affects: Organizations and IT administrators Started with KB5036386 · Mar 12, 2024

    After you install this security update (SU), the program no longer supports the Oracle Outside In Technology (OIT) or OutsideInModule

    Exchange no longer extracts text from JPEG, TIFF, or AutoCAD attachments for mail-flow checks. This can affect attachment rules.

    How to apply the workaround PowerShell

    A PowerShell script can override the setting that disables OIT. Microsoft advises against overriding it unless a functional issue affects the organization's mail flow.

No known issue matches these filters.