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Released: May 2025 Exchange Server Hotfix Updates

The_Exchange_Team's avatar
The_Exchange_Team
Platinum Contributor
May 29, 2025

Microsoft has released Hotfix Updates (HUs) that address issues in earlier updates for:

  • Exchange Server 2019
  • Exchange Server 2016

HUs are available for the following specific versions of Exchange Server:

  • Exchange Server 2019 CU14 and CU15
  • Exchange Server 2016 CU23

The May 2025 HUs do not contain any new Exchange Server security updates but contain fixes for non-security issues. Please see the release KB article for more information.

Because it has been listed as a “known issue” during a few recent releases, we wanted to call out that one of the issues addressed in this HU is Edge Transport service stops responding after installing November 2024 SU (if you worked around this issue in the past, please note there is a manual action needed to remove the override, as per the KB).

Reminder: Dedicated Exchange Hybrid Application support

We wanted to remind you that since our updates are cumulative, May 2025 HUs include support for creation of dedicated Exchange hybrid app originally released in April 2025 HU. Please see our April 2025 HU announcement as well as feature documentation and FAQ.

Update installation

The following update paths are available:

Hotfix Update FAQs

We installed the last Security Update. Should we install the later Hotfix Update?
Exchange Server HUs are optional updates, but they might introduce features or fixes that your organization can benefit from. Please see the release KB article for more details.

We did not yet install the earlier Security Update. Do we have to install the last available SU first before installing the later HU?
All of Exchange updates (HUs or SUs) are cumulative. Therefore, a newer SU or HU will contain all the changes that a previous, older SU or HU has. If you have not installed the older updates yet, you can install the newer one directly and skip the older one.

Our Exchange servers update automatically through Windows / Microsoft Update. Will our servers automatically install the HU update?
HUs will appear as an optional update for your servers. The update will also be available on the Microsoft Update Catalog after a few days of delay.

Will the new features and fixes released in the HU also be rolled into future updates, or must we install this specific HU to get them?
Content of this HU will be included in subsequent updates for Exchange Server.

Can HUs be uninstalled (if the need arises)?
Yes. HUs, like SUs, can be uninstalled.

Documentation may not be fully available at the time this post is published.

This post might receive future updates; they will be listed here (if available).

The Exchange Server Team

Updated Jun 04, 2025
Version 3.0
announcements
exchange 2016
exchange 2019
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24 Comments

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  • grant950's avatar
    grant950
    Copper Contributor
    Jun 19, 2025

    Can you guys comment on the functionality of a 2 node dag + witness server with exchange 2019 cu15 and server 2025. If i shut down 1 server the second server immediately fails. The issue seems to stem from the windows clustering side of things, get-cluster and get-clustergroup both return:  remote server has been paused or is in the process of being started.
        The remote server has been paused or is in the process of being started

     

    this never clears or changes.

     

    If i manually move the cluster off the node i intend to shut down everything works, but i have to do that proactively, i cant find a way to recover the second node with the other off. Turning the other server back on does fix the issue. I am not alone in this, per this forum: https://learn.microsoft.com/en-us/answers/questions/2247840/dag-failover-not-working-with-2-node-exchange-serv

     

    ill be honest though i am not convinced its specifically server 2025, i had this problem with server 2022 and attributed it to many in-place upgrades over the years. I just rebuilt this in a test environment from scratch and have the same issue immediately. I read the cluster logs before I wiped the original servers and unfortunately, i dont have the exact error, but it was basically saying, cant hit the other node, we have priority according to the quorum fileserver, but we arent going to do anything.

      • grant950's avatar
        grant950
        Copper Contributor
        Jun 20, 2025

        nothing is reported, i really think this isnt working right for anyone in a 2 node dag.

  • Peter222012144's avatar
    Peter222012144
    Copper Contributor
    Jun 19, 2025

    It was a long time since we had any problems with an exchange update but this time it happened.

    We did the same procedure as always fresh rebooted server after any windows update. Run the update in an elevated command prompt.

    This time we had run Windows update to apply June security updates to both of our Windows 2019 Servers in an Exchange 2019 CU15 DAG.

    First server issues after Exchange update:

    Installer told us processes was in use. Retry did not work for us. The same dialog appeared again. We decided to cancel it and skip the update for now. That did not work. After that all exchange service was in a disabled state. We tried to re-run the update and then it completed sucessfully. But still all services was in a disabled state. We put them in automatic start and rebooted the server. Got some error that Exchange service host terminated all the time. We found out that world wide web publishing service also had been disabled and IIS admin service. After enabling automatic start it worked.

    Second Server issues after Exchange update:

    Exchange update run successfully with out issues. Rebooted server. Thought everything was fine. Later users complained about HTTP error 500 (directory not found, or something like that). The update must have messed up the virtual directories for OWA. After googling we found that the updatecas.ps1 script found in exchange installation could repair. We tried that and it worked.

    So this time the patching was a nightmare.

  • Marcin69's avatar
    Marcin69
    Copper Contributor
    Jun 16, 2025

    After installing Exchange Server 2016 CU23 May25HU (15.1.2507.57), the M365 admin center "Software Updates" page displays it as "HU Apr 2025 + Hotfix". Naming discrepancy? I believe it can not be stalled status problem, as the server was not treated with Apr 2025 fix previously.

  • DaveUK's avatar
    DaveUK
    Copper Contributor
    Jun 12, 2025

    I keep my servers fully patched and installed all CU's, SU's and HU's to date, but I am strangely getting this error for the latest Hotfix, I've done all my usual steps of disabling AV and running the EXE from elevated CMD prompt and using my Domain admin account, but can't get past this, any suggestions please

     

    Thanks

    • Amer Anwar's avatar
      Amer Anwar
      Copper Contributor
      Jun 16, 2025

      Had the same experience on a few servers. In all cases the retry worked.

      • Peter222012144's avatar
        Peter222012144
        Copper Contributor
        Jun 17, 2025

        Had the same issue on a Windows 2019 Server with Exchange 2019 CU15. Retry did not work for us. The same dialog appeared again. We decided to cancel it and skip the update for now. That did not work. After that all exchange service was in a disabled state. We tried to rereun the update and then it completed sucessfully. But still all services was in a disabled state. We put them in automatic start and rebooted the server. All services started but now Microsoft Exchange Service Host service terminating every 20 second and in application log we see the following error...

        Watson report about to be sent for process id: 3384, with parameters: E12IIS, c-RTL-AMD64, 15.02.1748.026, M.Exchange.ServiceHost, M.Exchange.CertificateNotificationServicelet, M.E.S.CertificateNotificationServicelet.UpdateDataInMbx, System.ArgumentNullException, b164-dumptidset, 15.02.1748.026.
        ErrorReportingEnabled: True 

        Anyone have a clue about this?

        EDIT: (SOLVED)

        We found out that we missed to put World Wide Web Publishing Service to automatic. That service was also changed by the installer. After comparing the two servers in the DAG we could see what services that was automatic on the working server.

        It would be great if the installer in someway could return the server to a working state if cancel button is pressed. Or Exit button that was our only option when the Retry did not work.

  • Blakaboi's avatar
    Blakaboi
    Copper Contributor
    Jun 10, 2025

    Has anyone experience this when performing the installation of the HU from Windows core OS. 🤔🤷🏾‍♂️

     

  • steamrick's avatar
    steamrick
    Copper Contributor
    Jun 06, 2025

    I'm curious why this HU came out between two patchdays.

    The StoreWorker crashing sucks for those who have it, but it's not even mentioned in the blogpost, so it's probably not widely spread.

    The Edge Transport is mentioned, but there's a working workaround.

    What made you hit 'publish' at the end of May instead of the second tuesday of June?

    • Nino_Bilic's avatar
      Nino_Bilic
      Icon for Microsoft rankMicrosoft
      Jun 06, 2025

      There is a bit of a misunderstanding of what "patch Tuesday" (second Tuesday in a month) is for. Generally speaking, this "second Tuesday" is when various vendors (Microsoft included) release security updates, and non-security updates are released on a different Tuesday in the month, later. See this for the Windows release cadence (where the whole thing started).

      In other words - we release on second Tuesday if it is a security fix. If it is not, we release later in the month. If you look at our page that lists all releases, you'll notice that HUs are never released on second Tuesday. We target third Tuesday with non-security releases but might release later in the month also as we'd rather release than wait for some "date on the calendar" for non-security updates.

  • karil222's avatar
    karil222
    Copper Contributor
    Jun 03, 2025

    If the workaround (setting override) for the Edge Transport crashing was implemented, does this HU remove it during installation? If doesn't, are there any specific instructions etc to do it manually? Eg. should the existing override be removed prior to installing new HU, or afterwards?

    • LukasSMSFT's avatar
      LukasSMSFT
      Icon for Microsoft rankMicrosoft
      Jun 03, 2025

      The Setting Override remain unchanged after installing the May 2025 Hotfix Update. You can remove it by running the following PowerShell commands:

       

      Get-SettingOverride | Where-Object {$_.ComponentName -eq  "Encryption" -and $_.SectionName -eq "UseMSIPC" -and $_.Parameters -eq "Enabled=false"} | Remove-SettingOverride

Get-ExchangeDiagnosticInfo -Process Microsoft.Exchange.Directory.TopologyService -Component VariantConfiguration -Argument Refresh 

Restart-Service MSExchangeTransport

       

  • FourK95's avatar
    FourK95
    Copper Contributor
    Jun 03, 2025

    We are curently experiencing the issue that our WSUS wont show this or any other Update since November 2024. KB5050674 cannot be found on the calatog server site (catalog.update.microsoft.com), is it that the HU/SU/CU functionality is removed from the catalog Update Servers for WSUS/SCCM?

    • Nino_Bilic's avatar
      Nino_Bilic
      Icon for Microsoft rankMicrosoft
      Jun 03, 2025

      It is expected that April HU did not show up there. May HU is coming, but this takes some time after the main release as it is a separate deployment (long story).

    • Nino_Bilic's avatar
      Nino_Bilic
      Icon for Microsoft rankMicrosoft
      Jun 03, 2025

      This was a customer reported issue that we have addressed in this HU. We only had a few reports of this problem but it was significant for those that had it as mailboxes would be quarantined (you'd know).