Application pool stops responding and performance is affected after MSIPC is enabled

Symptoms 

After you install the November 2024 or later Microsoft Exchange Server security update, the Active Directory servers experience high CPU usage or applications might stop responding. This issue causes application pools to get recycling on the Exchange server, and Microsoft Outlook gets disconnected from the server. 

Cause 

This issue occurs because MSIPC is enabled by default in Exchange Server 2016, 2019 and Subscription Edition. For more information, see MSIPC enabled by default in Exchange Server 2019 and 2016. 

Resolution

To fix this issue, install the following security updates:

• Description of the security update for Microsoft Exchange Server Subscription Edition RTM: August 12, 2025 (KB5063224)

• Description of the security update for Microsoft Exchange Server 2016: August 12, 2025 (KB5063223)

• Description of the security update for Microsoft Exchange Server 2019: August 12, 2025 (KB5063222)

• Description of the security update for Microsoft Exchange Server 2019: August 12, 2025 (KB5063221) 

If you've enabled the setting override as a workaround for the application not responding, you can remove the override after you install this update. To remove the setting override, run the following commands by using an elevated Exchange Management Shell (EMS) instance: