Hi,
Thanks for posting in Microsoft Q&A forum.
1,What version of MDT and Windows ADK you are using? Have you uninstall the Windows ADK and WinPE add-on, and then install the latest version of Windows ADK and WinPE add-on? Starting with Windows 10, version 1809, the Windows Preinstallation Environment (PE) is released separately from the Assessment and Deployment Kit (ADK), so we also need install WinPE add-on.
Similar thread for your reference: Unable to open the specified WIM file – error in MDT after upgrading to ADK 1809
2, Maybe the error is caused by antivirus software prventing access to the files. Please disable the antivirus software and restart your MDT server to have a try. Similar thread for your reference: Getting caught by your own permissions!
Please note: The links are not from Microsoft, just for your reference. Thanks for your time.
Best regards,
Simon
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