Windows Activation Error

0xC004E016: Product key invalid (format error)

0xC004E016 means the Software Licensing Service rejected the entered product key during local validation, before it even reaches the server. The most common causes are a mistyped key or a key that belongs to a different product (for example entering an Office key into Windows). Entering the correct key by hand, in full, usually resolves it.

Most common causes

• The key was entered incomplete or with a wrong character
• The key belongs to another product (Office, Windows Server)
• The key was copied truncated or with stray spaces instead of 25 characters
• The licensing service is corrupted (rare)

Step-by-step fix

1. Check your purchase e-mail to confirm which product the key is for; a Windows key only works in Windows.
2. Under Settings → System → Activation → "Change product key", type the key by hand in five blocks of five.
3. In an elevated Command Prompt run "slmgr /ipk KEY" then "slmgr /ato"; if the command errors, the key format is wrong.
4. In "services.msc" verify the "Software Protection" service is running; start it if it is stopped.
5. If you still get 0xC004E016, have your seller verify the key.

Frequently Asked Questions

Other activation errors

• 0xC004C003Product key blocked
• 0xC004C008Key usage limit exceeded
• 0xC004F050Invalid product key (edition mismatch)
• 0xC004F074KMS server could not be reached