Office 0xC004C003: Microsoft has blocked this product key permanently
Error 0xC004C003 means Microsoft blocked the Office key, usually a resold or grey-market licence. Here is why it happens and what actually fixes it.
0xC004B001 and 0xC004B100: Activation Server Says the Licence Is Invalid
0xC004B001 and 0xC004B100 mean Microsoft servers refused to activate this computer licence. Learn what triggers the refusal and which licence fixes it.