DISM error 87 in windows occurs because of errors in the DISM command itself, such as syntax errors, incorrect spacing, or unsupported options. In order to fix the problem, you need to type the above-mentioned command into Command Prompt as an administrator:
DISM.exe /Online /Cleanup-Image /RestoreHealth
Then press Enter and let it complete. If you wish to scan the file store first, use DISM.exe /Online /Cleanup-Image /ScanHealth. You must be sure that the command is run in a standard Windows environment, and not an unsupported recovery environment. Once DISM completes without any problems, run sfc /scannow to check Windows system files.
