How to Fix Affinity Crashing on macOS Sonoma With OCLP

Stop Affinity from crashing the moment you open a file on an older Mac running macOS Sonoma through OpenCore Legacy Patcher, by moving to a macOS version your GPU's drivers can handle.

By Petrus Sheya

October 8, 2026 · 4 min read

Affinity crashes when you open a file because it tries to draw with GPU features that the legacy Metal drivers on older GPUs, like NVIDIA Kepler cards, don't have. The fix that works is to go back to macOS Ventura or Monterey, where those old drivers behave better.

This happens on Intel Macs running a newer macOS than Apple supports, through OpenCore Legacy Patcher (OCLP). The app opens fine, then quits the moment a document loads. There's no setting inside Affinity that brings the missing GPU features back, which is why a downgrade is the real fix.

How to downgrade macOS with OpenCore Legacy Patcher

  1. Back up your files. Copy your documents, Affinity files and anything else you need to an external drive. You can't install an older macOS on top of a newer one, so the disk gets erased.
  2. Download an older macOS installer. Open OpenCore Legacy Patcher, click Create macOS Installer, then Download macOS Installer and pick Ventura or Monterey from the list.
  3. Flash the installer to a USB drive. Plug in a USB drive of at least 16 GB, select it when OCLP asks, and let it write the installer. Say yes when it offers to install OpenCore on the USB drive.
  4. Boot from the USB drive. Restart and hold Option. Pick EFI Boot, then pick the macOS installer from the OpenCore menu.
  5. Erase the internal disk. Open Disk Utility from the installer window, select your internal disk and click Erase. Use the APFS format.
  6. Install macOS. Quit Disk Utility, choose Install macOS and pick the disk you just erased. The Mac restarts a few times. Pick the internal disk in the OpenCore menu each time if it asks.
  7. Run the root patches. Once you reach the desktop, open OpenCore Legacy Patcher (install it again from the USB if it's missing), click Post-Install Root Patch, then Start Root Patching, and restart. This puts the legacy graphics drivers back. Without it, your GPU runs with no proper driver at all.
  8. Reinstall Affinity and open a file. Copy your files back from the external drive, install Affinity again and open a document. It should load without crashing.

If you still see glitches or slow drawing after the downgrade, check the GPU temperature before you blame the software. The next section covers that.

Turn off Metal acceleration in Affinity

Before you erase anything, you can try telling Affinity to stop using the GPU for its heavy lifting.

  1. Open Affinity and go to Affinity > Settings (or Preferences) > Performance.
  2. Untick Enable Metal compute acceleration.
  3. Quit Affinity, open it again and open a file.

Don't expect much from this one. A 2013 Mac Pro on Ventura still crashed with Metal both on and off, so treat it as a quick test, not a fix.

Check your GPU thermals and repaste it

On a Mac that's 10 years old or more, the thermal paste on the GPU is usually dried out. The GeForce GT 755M in the late 2013 iMac runs hot, and an overheating GPU makes the driver fall over more often, which looks a lot like an app crash.

  1. Install a temperature monitor and watch the GPU temperature while you work in Affinity.
  2. If it runs very hot under load, open the Mac and replace the old paste with a thermal pad like PTM7950.

This won't fix the Sonoma crash on its own. It helps if you keep seeing acceleration problems after the downgrade, or if you push the GPU hard.

FAQ

Can I fix the crash without leaving Sonoma? Not really. The crash comes from Affinity calling GPU features that the patched legacy Metal drivers don't have, and no setting in Affinity or OpenCore Legacy Patcher adds them back. Turning off Metal acceleration is worth a quick try, but don't count on it.

Which Macs hit this crash? Mostly Macs with NVIDIA Kepler GPUs, like the late 2013 iMac with a GeForce GT 755M, running Sonoma through OpenCore Legacy Patcher. That iMac has no built-in Intel graphics to fall back on, so when the Kepler driver fails, the app goes down with it.

Does downgrading fix it on a 2013 Mac Pro? Not always. A 2013 Mac Pro with AMD FirePro graphics on Ventura and OpenCore Legacy Patcher 2.4.0 still crashed when zooming in both the vector and pixel views, with Metal on or off. Ventura or Monterey is the best bet, but on that machine you may still see crashes.

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