Troubleshooting Windows Upgrade Issues: Access Denied Error

January 6, 2026 3 answers
Asked by TechieTurtle47
I'm trying to automatically upgrade our PCs from Windows 10 Enterprise LTSC to Windows 11 Enterprise LTSC using a script that runs through a scheduled task via Group Policy with the SYSTEM account. This worked fine on my VM and on one of my colleagues' computers who has admin access. However, when I rolled out the GPO to another team, the upgrade process started but failed with an 'Access is denied' error after copying and mounting the ISO. What steps can I take to troubleshoot this issue? Any suggestions would be really helpful!

Answers

DebuggingDude99
Have you checked the setup error log for more details? It's also worth looking into what command you're using to run the setup. Sometimes the mounting can happen in the user session, which could lead to permission issues. Also, consider if any antivirus or other protection software might be interfering with the setup process.
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LogMaster123
Have you had a look at the setuperr.log file? It might give you more insights into why the setup is being blocked.
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SecuritySleuth22
Make sure to verify if any endpoint protection software or HVCI (Hypervisor-protected Code Integrity) is enabled on those machines. It can block the setup if Windows Defender Application Control policies are overly strict or if Credential Guard is interfering with the SYSTEM account's access.
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