Look at the logs. If you see Sysprep_Clean_Validate_Opk then is a pending Windows update in progress. Finish Windows Updates then try again.

• 2021-06-17 09:22:22, Error                 SYSPRP Sysprep_Clean_Validate_Opk: Audit mode cannot be turned on if reserved storage is in use. An update or servicing operation may be using reserved storage.; hr = 0x800F0975

• 2021-06-17 09:22:22, Error                 SYSPRP ActionPlatform::LaunchModule: Failure occurred while executing 'Sysprep_Clean_Validate_Opk' from C:\Windows\System32\spopk.dll; dwRet = 0x975

• 2021-06-17 09:22:22, Error                 SYSPRP SysprepSession::Validate: Error in validating actions from C:\Windows\System32\Sysprep\ActionFiles\Cleanup.xml; dwRet = 0x975

• 2021-06-17 09:22:22, Error                 SYSPRP RunPlatformActions:Failed while validating Sysprep session actions; dwRet = 0x975

• 2021-06-17 09:22:22, Error      [0x0f0070] SYSPRP RunDlls:An error occurred while running registry sysprep DLLs, halting sysprep execution. dwRet = 0x975

• 2021-06-17 09:22:22, Error      [0x0f00d8] SYSPRP WinMain:Hit failure while pre-validate sysprep cleanup internal providers; hr = 0x80070975

• 2021-06-17 12:10:18, Error                 SYSPRP Sysprep_Clean_Validate_Opk:There are one or more Windows updates that require a reboot. To run Sysprep, reboot the computer and restart the application.[gle=0x000036b7]

• 2021-06-17 12:10:18, Error                 SYSPRP ActionPlatform::LaunchModule: Failure occurred while executing 'Sysprep_Clean_Validate_Opk' from C:\Windows\System32\spopk.dll; dwRet = 0x139f[gle=0x000036b7]

• 2021-06-17 12:10:18, Error                 SYSPRP SysprepSession::Validate: Error in validating actions from C:\Windows\System32\Sysprep\ActionFiles\Cleanup.xml; dwRet = 0x139f

• 2021-06-17 12:10:18, Error                 SYSPRP RunPlatformActions:Failed while validating Sysprep session actions; dwRet = 0x139f

• 2021-06-17 12:10:18, Error      [0x0f0070] SYSPRP RunDlls:An error occurred while running registry sysprep DLLs, halting sysprep execution. dwRet = 0x139f

• 2021-06-17 12:10:18, Error      [0x0f00d8] SYSPRP WinMain:Hit failure while pre-validate sysprep cleanup internal providers; hr = 0x8007139f

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