| Problem | Solution | |---------|----------| | Installation freezes at 0% | Run installer as Administrator, disable antivirus temporarily | | "Invalid serial number" error | Ensure you're using Autodesk-provided credentials, not web-found keys | | Missing .NET Framework error | Install .NET 4.6+ from Microsoft before AutoCAD | | DirectX error | Update graphics drivers and DirectX from Microsoft | | Activation limit exceeded | Contact Autodesk support—they can reset activation counts |