
Deployment Image Servicing and Management (DISM) is a tool that allows you to service your images offline. Here are some DISM related errors, Failure 5627: How to fix error 0x800f0805, run DISM executable, Error 0xc1420127: The specified image in the specified wim is already mounted for read and write access. Before I proceed with the steps to resolve this issue, I would like to explain some key differences between mounting and unmounting a wim file. Suppose you need to change a WIM file by adding or removing packages. In that case, you must mount it properly on Windows using DISM, a command line that enumerates, installs, uninstalls, configures, and updates features and packages in Windows images.
See the following guides for more details on ADK, MDT, Microsoft Endpoint Configuration Manager (SCCM), Intune, Autopilot, and WSUS. Also, see how to configure and deploy Windows using Microsoft Deployment Toolkit, and Windows Deployment Services for Windows 10 (ADK, MDT, and WDS).
After you modify a mounted image, you must unmount it. If you mounted your image with the default read/write permissions, you can commit your changes. This makes your modifications a permanent part of the image.
0xc1420117 Error Incomplete Unmounting Due to Open Files
You may encounter this issue when mounting an image (install.wim) file. The “0xc1420117 Error Incomplete Unmounting Due to Open Files” occurred when I tried to mount a new Windows image, due to leftover residue in the previous mount point. See the following hyperlink for more details on ADK, MDT, Microsoft Endpoint Configuration Manager (SCCM), Intune, Autopilot, and WSUS. Also, see how to configure and deploy Windows using Microsoft Deployment Toolkit, and Windows Deployment Services for Windows 10 (ADK, MDT, and WDS).

Step 1: Only perform this step if you have some residue folder left in the mounted directory (folder).
– To resolve the 0xc1420117 error, delete these folders before mounting the wim file again. See this guide on going about this issue “The action cannot be completed because the folder or file is open in another program: How to determine where a file is open in windows“.
Step 2:Now that you’ve removed the folders, execute the command to unmount the Windows Image (install.wim file), optimizing it for your environment.
Dism /Unmount-image /MountDir:<target_mount_directory> {/Commit | /Discard}
After unmounting the win file, you should be able to address the 0xc1420117 Error Incomplete Unmounting Due to Open Files and then proceed to mount your Windows image again. Continue with the modification by using the command below. Please modify this command to reflect your information. For more information, see the following guide on how to mount and unmount a Windows image file.
DISM /Mount-Wim /WimFile:"filename.wim" /index:3 /MountDir:"c:\temp"
I hope you found this blog post about the 0xc1420117 Error Incomplete Unmounting Due to Open Files helpful. Please let me know in the comment session if you have any questions.