Fix 0xC0262502: GPU driver UAB not supported

This DirectX error hits when your GPU driver can't handle a user-accessible bus request, often after a driver update or hardware swap. The fix is usually a clean driver reinstall or a GPU replacement.

When does this error show up?

You'll see 0xC0262502 (ERROR_GRAPHICS_UAB_NOT_SUPPORTED) when launching a DirectX 12 game or rendering app on a mid-range GPU like an Nvidia GTX 1060 or AMD RX 580. The error pops up right after the splash screen, then the app crashes. It's common after a Windows update or a GPU driver upgrade — especially when the new driver drops support for older hardware features.

Root cause

The user-accessible bus (UAB) is a DirectX 12 feature that lets the GPU driver expose a direct memory-mapped I/O region to user-mode apps. Older GPUs or outdated drivers simply don't support it. The culprit is almost always a driver that's too new for the hardware or vice versa — for instance, installing the latest Nvidia Game Ready driver on a GTX 700 series card. Windows Update can also push a driver that doesn't match your GPU model.

Step-by-step fix

Run DDU to nuke the current driver. Download Display Driver Uninstaller (DDU) from Guru3D. Boot into Safe Mode. Run DDU and select your GPU vendor — Nvidia or AMD. Let it clean the driver completely. Restart normally.
Install the correct driver. Don't grab the latest driver from the manufacturer's site blindly. For older GPUs, go back 3-4 driver versions. For Nvidia, use the Studio driver branch — it's more stable. For AMD, pick the Adrenalin Edition that matches your card's release era. Install without GeForce Experience or Adrenalin Software — just the driver itself.
Disable Windows automatic driver updates. Open System Properties > Hardware > Device Installation Settings. Select No (your device might not work as expected). This stops Windows from overwriting your driver after a reboot.
Verify DirectX version. Run dxdiag from Start menu. Check the Display tab — make sure DirectX 12 is listed as supported. If not, your GPU might be too old. A GTX 600 series or Radeon HD 7000 won't work with D3D12 UAB.
Test with a different app. Try another DirectX 12 game like Forza Horizon 4 or Shadow of the Tomb Raider. If the error repeats, the driver isn't the problem.

Still failing?

If the error persists after a clean driver install, your GPU's hardware doesn't support UAB. This happens with cards like the GTX 750 Ti or Radeon R9 270 — they technically support DirectX 12 but lack the IOMMU capability needed for UAB. Your only option here is a GPU upgrade. An RX 6600 or RTX 3050 will fix it. Also check your motherboard's BIOS — disable Above 4G Decoding if it's on, as that can conflict with UAB on some boards. I've seen that trip up people on B450 chipsets with Ryzen processors.

One last thing: if you're running a laptop with switchable graphics (like Intel+Nvidia Optimus), the error can come from the iGPU trying to use UAB. Force your dedicated GPU for the app via Nvidia Control Panel or Windows Graphics Settings. That's a common miss.