Hey Checkyourlogs Fans,

Microsoft Exchange Server 2019 Hotfix KB50557651 (Cumulative Update 15 Hotfix) is an optional update designed to enhance the server’s security and stability. It addresses several non-security bugs introduced in earlier updates and includes all previously released security fixes. In short, applying this hotfix helps resolve known issues (e.g. the Edge Transport service hanging) and ensures your Exchange 2019 server on CU15 has the latest enhancements and protections. It’s recommended for organizations running Exchange 2019 CU15 to improve overall reliability.

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GUI-Based Installation Steps

Before starting, confirm that your server is running Exchange 2019 Cumulative Update 15 (CU15). This hotfix applies only to servers on that cumulative update level. In a single-server environment (where all roles are on one machine), plan for a brief maintenance window, as Exchange services will be restarted during the update.

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  1. Download the Hotfix: Obtain the hotfix package from Microsoft. You can either use Windows Update (it’s offered as an Optional update for Exchange 2019 CU15) or download the standalone installer from the Microsoft Download Center. The update file is named Exchange2019-KB5057651-x64-en.exe (note that the KB number in the filename may appear as KB5057651 for this CU15 hotfix). Save this file to the Exchange server.
  2. Prepare for Installation: It’s good practice to temporarily turn off any antivirus software during the update (to prevent interference). Close any open Exchange Management Shell or Console sessions. Ensure there are no pending Windows reboots on the server (install any required OS updates and reboot first if needed).
  3. Launch the Installer: Run the hotfix installer on the Exchange server (double-click the .exe or run it via an elevated PowerShell prompt). A setup wizard will open for the “Exchange Server 2019 Hotfix Update.” Follow the GUI prompts by clicking Next and accepting the license terms to begin the installation. The wizard will automatically stop Exchange services and apply the patch to your Exchange 2019 installation.

The Exchange Server 2019 Hotfix Update Setup wizard will install the patch for Cumulative Update 15 (CU15). The UI will show progress (as above) while it updates Exchange files for KB5057651. This process may take several minutes. Please wait for the setup to complete, and do not interrupt it until you see a completion message.

  1. Completion: Once the setup is complete, it will indicate that the hotfix has been installed successfully. Click Finish to close the wizard. If you had disabled antivirus earlier, re-enable it now. The installer may prompt for a reboot; if it does not, plan to restart the server manually as a final step. A reboot ensures all services come up with the updated binaries.

Post-Installation: Reboot and Version Verification

Reboot: A server restart is generally required to finalize the hotfix installation (and the setup program may prompt you to reboot). After installation, reboot the Windows Server 2022 host to ensure all Exchange services start cleanly with the updated components.

Verify the New Version: After the server restarts, verify that Exchange 2019 has been updated to the correct build version. You can check this via PowerShell or the Exchange Admin Center. For example, in the Exchange Management Shell, run:


Get-Command Exsetup.exe | ForEach-Object { $_.FileVersionInfo }

This command retrieves the file version of the Exchange setup binary, which reflects the current Exchange build. After applying Hotfix KB50557651, the Exchange 2019 version should show as 15.2.1748.26 (indicating CU15 plus the hotfix). You should see this build number in the output or Exchange’s About page.

Thanks,

Dave Kawula – MVP