If you need modern DISM features (like /RestoreHealth with Windows Update), you must update the tool via KB2966583. Otherwise, stick to the legacy tool—it is slow, but it works on 100% of Windows 7 machines, regardless of update status.
Microsoft backported some DISM features to Windows 7 via an update (KB2966583), but the version shipped with Windows 7 natively does support the commands you see in modern Windows 10 guides. how to fix error 87 dism windows 7
If so, move to Fix 2. Fix 2: Update Your Windows 7 DISM Tool (The "KB2966583" Fix) If you receive Error 87 even when using the /Source parameter, your DISM binary is too old to understand the /RestoreHealth argument at all. If you need modern DISM features (like /RestoreHealth