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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
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12 Comments

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  • 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).