Fix Firefox EXC_BAD_ACCESS crash on macOS Ventura

Quick answer for advanced users

Disable hardware acceleration in Firefox settings or run in Safe Mode (hold Option while launching). If that stops the crash, the GPU driver or Firefox version is the problem. Update Firefox to 118+ or switch to an ESR release.

Why this happens

EXC_BAD_ACCESS is a memory access violation — Firefox tried to read or write memory it didn't own. On macOS Ventura, this usually hits when Firefox uses your GPU to render WebGL or complex CSS. The trigger is almost always a specific site with heavy GPU work: interactive maps, WebGL games, or video conferencing tools. If you're on Firefox 115-117 on Ventura 13.4-13.6, you're likely hitting a known bug where the GPU driver and Firefox's compositor don't play nice.

The crash doesn't happen in Safari or Chrome because they use Apple's WebKit or Chromium's GPU stack differently. Firefox's own compositor (WebRender) tangles with the Metal API in just the wrong way on some Mac hardware — especially Intel Macs and M1/M2 machines running Rosetta.

Fix step by step

Update Firefox — Go to Firefox menu > About Firefox. Let it download the latest version (118+ as of this writing). Restart. Mozilla patched this in 118.0.1.
Disable hardware acceleration — Open Firefox, go to Preferences > General > Performance. Uncheck "Use recommended performance settings". Then uncheck "Use hardware acceleration when available". Restart Firefox.
Reset WebRender — Type about:config in the address bar, accept the risk. Search for gfx.webrender.all. Set it to false. Also set layers.acceleration.disabled to true.
Clear GPU cache — Close Firefox. Open Terminal. Run:
```
rm -rf ~/Library/Caches/Firefox/Profiles/*/gfx-cache/
```
Then restart Firefox.
Test in Safe Mode — Hold the Option key and click Firefox. Choose "Start in Safe Mode". If the crash stops, an extension or theme caused it. Disable all add-ons, then re-enable them one by one.

If the main fix fails

Sometimes the problem isn't hardware acceleration — it's a corrupted profile. Try this:

Create a new profile — Quit Firefox. Go to Terminal and run:
```
firefox -CreateProfile testuser
```
Launch Firefox with:
```
firefox -P testuser
```
If no crash, your old profile is toast. Migrate bookmarks and passwords from the old profile folder.
Use Firefox ESR — Download Firefox ESR 115.x from Mozilla's site. It's a slower release cycle that skips buggy GPU changes. Install it alongside your normal Firefox. Test the same sites.
Disable WebGL — In about:config, set webgl.disabled to true. This kills all WebGL content — 3D graphics, some video effects — but stops the crash cold. Only do this if you don't need 3D in the browser.

Prevention tip

Don't let Firefox auto-update to the latest version immediately. Wait a week after a major release to check forums for crash reports. I pin Firefox to an ESR version on production machines for a reason — it saves these headaches. Also, keep macOS updated. Apple fixed similar Metal API crashes in Ventura 13.6.1.

One more thing: if you're on an Intel Mac, check if you're running Firefox under Rosetta. Go to Applications, right-click Firefox, Get Info, and see if "Open using Rosetta" is checked. Uncheck it if so — native ARM builds of Firefox (118+) don't have this crash.