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Important
An upcoming change to Windows, included in the April 2026 Windows Server update, the default Kerberos encryption type is changing from RC4 to AES-SHA1.
File shares hosting FSLogix containers that aren't upgraded to AES-SHA1 might have access issues after this change is applied. To avoid disruption, complete the upgrade to AES-SHA1 before installing the update.
Customers who have already upgraded to AES-SHA1 aren't affected.
For more information, see the FSLogix blog: Action required: Windows Kerberos hardening (RC4) may affect FSLogix profiles on SMB storage.
Virtual machine size (user density)
In multi-session environment where multiple users can connect to the same virtual machine, sizing and optimal user density are important factors for a good user experience.
Recommendations
- Reduce the number of concurrent users per virtual machine
- Increase the size of the virtual machine
- vCPU only
- Memory only
- vCPU and Memory
- If using a Cloud Cache configuration, start with a 2:1 user to vCPU ratio.
Virtual machines shows high CPU usages for svchost.exe
In some situations, high CPU usage for svchost.exe can be caused by Distributed Component Object Model (DCOM) permissions. DCOM in Windows allows remote communication between applications. Resetting the DCOM permission stack allows the components to reset their correct permissions and may resolve the application instability and high CPU usage.
Recommendation
Warning
Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
Reset DCOM permissions by removing the following entries from the registry:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole:"DefaultAccessPermission"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole:"DefaultLaunchPermission"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole:"MachineAccessRestriction"HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Ole:"MachineLaunchRestriction"