Typically displayed in the Command Prompt as Error: 87 – The option is unknown , this error halts your repair efforts immediately. While the message sounds vague, it is actually a very specific syntax error. The good news? It is almost always fixable within minutes.
Missing colon after Online .
DISM \Online \Cleanup-Image Right: DISM /Online: /Cleanup-Image dism error 87 fixed
By carefully reviewing your command, ensuring /Online: has the colon, and running the tool with administrative privileges, you will resolve this error in under two minutes. For the rare cases where the error persists, repairing your system files with SFC or switching to PowerShell will get the job done. Typically displayed in the Command Prompt as Error:
DISM /Online /Cleanup-Image /RestoreHealth Result: Error: 87 – The option is unknown. It is almost always fixable within minutes
| Cause | Explanation | | :--- | :--- | | | Missing spaces, extra slashes, or misspelled words (e.g., Ckeanup instead of Cleanup ). | | Missing colons | Forgetting the colon after Online ( /Online: is required, not just /Online ). | | Wrong slashes | Using backslashes ( \ ) instead of forward slashes ( / ). | | Incorrect command order | DISM is sensitive to the sequence of arguments. | | Corrupt DISM binary | Rare, but possible if system files are damaged. |