Safari tabs that go to sleep display as completely blank pages when you try to navigate back to them. The tab appears to be loading (address bar shows loading indicator) but nothing ever appears. Reloading, Command+R, quit/restart Safari, and even rebooting the Mac don’t fix it. It affects all websites and it happens as soon a tab goes to sleep.
Workaround: Opening a new tab and pasting the same URL works fine - the issue is specifically with waking sleeping tabs.
JavaScript Console Errors:
I used the Safari Web Inspector to check the JavaScript console and found the following errors
Info] Successfully preconnected to https://media.kit.com/
[Info] Successfully preconnected to https://cdn.growthbook.io/
[Error] WebGL: context lost.
getContext
Ze (5217515.js:22:104828)
Ge (5217515.js:22:103197)
s (5217515.js:22:74190)
(anonymous function) (5217515.js:22:78314)
Promise
P (5217515.js:22:78288)
(anonymous function) (5217515.js:22:74360)
[Warning] The resource https://cdn.growthbook.io/api/features/sdk-fEXdMFz2U83CNTh was preloaded using link preload but not used within a few seconds from the window's load event. Please make sure it wasn't preloaded for nothing.
Working with Claude, I got the following: The “WebGL: context lost” error is the smoking gun - Safari’s GPU rendering is crashing when tabs wake from sleep.
Workaround
Disabled all GPU features in Safari:
- Safari > Settings > Advanced > “Show features for web developers”
- Develop menu > Experimental Features > Disable:
- GPU Process: Canvas Rendering
- GPU Process: DOM Rendering
Based on Claude’s advice I also ran the following command:
`sudo killall -HUP mDNSResponder
Which is odd, because can’t how the mDNSResponder helps with the GPU issue.
I restarted Safari and the issue went away.
Strangeness
I was really bugged that I can’t find another report of this issue. Anywhere. My wife’s MacBook Air is about as clean as it gets. I’m the the outrageous one installing apps and extensions, it should me with a weird issue like this.
Even more strange, I re-enabled all the GPU features, restarted Safari and the problem hasn’t returned.
I don’t expect a magic answer, I’m hoping someone will stumble across this later and tell me what I missed.