Missing spaces before forward slashes ( / ) is the #1 cause.
Before jumping into the fixes, it helps to understand why this error happens. The most common triggers include:
The core principles of DISM command syntax, the need for administrator privileges, and the steps to reset Windows Update have remained consistent across Windows 10 and Windows 11, and will likely remain valid for the foreseeable future.
DISM /Online /Cleanup-Image /RestoreHealth Result: Error: 87 – The option is unknown.
Since DISM often uses Windows Update to download "healthy" files to replace corrupted ones, a bug in the update system can trigger Error 87. Press Win + I to open .
The Deployment Image Servicing and Management (DISM) tool is a built-in Windows utility designed to repair corrupted system images. However, when trying to run a repair command, you might be blocked by a frustrating message:
Sometimes the DISM command parser itself becomes corrupted. Run SFC first:
| Purpose | Command | |--------|---------| | Check health | DISM /Online /Cleanup-Image /CheckHealth | | Scan only | DISM /Online /Cleanup-Image /ScanHealth | | Restore health (default) | DISM /Online /Cleanup-Image /RestoreHealth | | Use custom source | DISM /Online /Cleanup-Image /RestoreHealth /Source:E:\sources\install.wim |
The you typed right before the error appeared. Your Windows version (Windows 10 or 11).
It didn't error out immediately. It was working.
Ultimate Guide: How to Fix DISM Error 87 in Windows 10 and 11
DISM relies heavily on the Windows Update infrastructure to pull clean source files. If the Windows Update service is frozen, DISM will fail. Resetting the service fixes this link. Press to open the Run dialog box. Type services.msc and press Enter . Scroll down and locate Windows Update .
Follow these best practices to never see Error 87 again:
: DISM.exe /Online /Cleanup-image/Restorehealth (Missing a space before /Restorehealth ) Correct : DISM.exe /Online /Cleanup-image /Restorehealth How to run it correctly: Press the Windows Key . Type cmd . Right-click Command Prompt and select Run as administrator . Carefully type or copy-paste the exact string below: DISM.exe /Online /Cleanup-image /Restorehealth Use code with caution. Press Enter . 2. Run the SFC Tool First
Right-click on and select Run as administrator . Click Yes on the User Account Control (UAC) pop-up. 🔍 Advanced Troubleshooting
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Dism Error 87: Fixed __top__
Missing spaces before forward slashes ( / ) is the #1 cause.
Before jumping into the fixes, it helps to understand why this error happens. The most common triggers include:
The core principles of DISM command syntax, the need for administrator privileges, and the steps to reset Windows Update have remained consistent across Windows 10 and Windows 11, and will likely remain valid for the foreseeable future.
DISM /Online /Cleanup-Image /RestoreHealth Result: Error: 87 – The option is unknown.
Since DISM often uses Windows Update to download "healthy" files to replace corrupted ones, a bug in the update system can trigger Error 87. Press Win + I to open . dism error 87 fixed
The Deployment Image Servicing and Management (DISM) tool is a built-in Windows utility designed to repair corrupted system images. However, when trying to run a repair command, you might be blocked by a frustrating message:
Sometimes the DISM command parser itself becomes corrupted. Run SFC first:
| Purpose | Command | |--------|---------| | Check health | DISM /Online /Cleanup-Image /CheckHealth | | Scan only | DISM /Online /Cleanup-Image /ScanHealth | | Restore health (default) | DISM /Online /Cleanup-Image /RestoreHealth | | Use custom source | DISM /Online /Cleanup-Image /RestoreHealth /Source:E:\sources\install.wim |
The you typed right before the error appeared. Your Windows version (Windows 10 or 11). Missing spaces before forward slashes ( / ) is the #1 cause
It didn't error out immediately. It was working.
Ultimate Guide: How to Fix DISM Error 87 in Windows 10 and 11
DISM relies heavily on the Windows Update infrastructure to pull clean source files. If the Windows Update service is frozen, DISM will fail. Resetting the service fixes this link. Press to open the Run dialog box. Type services.msc and press Enter . Scroll down and locate Windows Update .
Follow these best practices to never see Error 87 again: The Deployment Image Servicing and Management (DISM) tool
: DISM.exe /Online /Cleanup-image/Restorehealth (Missing a space before /Restorehealth ) Correct : DISM.exe /Online /Cleanup-image /Restorehealth How to run it correctly: Press the Windows Key . Type cmd . Right-click Command Prompt and select Run as administrator . Carefully type or copy-paste the exact string below: DISM.exe /Online /Cleanup-image /Restorehealth Use code with caution. Press Enter . 2. Run the SFC Tool First
Right-click on and select Run as administrator . Click Yes on the User Account Control (UAC) pop-up. 🔍 Advanced Troubleshooting
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later.