Solve Error 0xC004C008 – “Key Already in Use on Another Device”
If you’re seeing error 0xC004C008, it typically means Microsoft’s activation system believes the product key has already been used on another device, or it has been activated too many times within a short period.
What this message usually indicates
This can happen with transferable or device-bound keys when:
The key was entered multiple times (on the same PC or different PCs)
Windows was reinstalled, or major hardware was changed (for example, a motherboard replacement)
Microsoft flags the key as requiring an alternate verification method (such as phone activation)
What to do next
Phone activation can sometimes resolve this, but we understand it can be inconvenient.
If you see 0xC004C008, contact us and we’ll help you get activated quickly. In many cases, we can provide a replacement key to keep the process simple and stress-free.