After updating SketchUp and macOS Tahoe, SketchUp began freezing with CPU pegged at ~100%. Multiple hidden SketchUp processes were left running instead of being cleaned up, causing new launches to stack on top of old ones. This appears to be a macOS Tahoe + SketchUp interaction issue (Cocoa/AppKit), likely triggered by extensions or UI threads that previously worked but now deadlock under the updated OS. The behavior did not occur before these updates.
There are a couple of topics about this behavior. Search the forum for “zombie”. For me they happen after I force-quit a beachballing SketchUp process via the dock menu. They have only one thread and no GUI, so can’t be accessed in any normal way.
They can cause issues such as files opening read only because macOS thinks they still have the last file open.
The devs have been told about this, but said they couldn’t reproduce the problem, so no known explanation or progress toward a fix.
You can clean them up from the Activity Monitor page you showed by double-clicking one, selecting quit at the bottom of the dialog that opens, and selecting force quit. A system restart will also clear them out because it kills all processes.
Well, I’m glad I’m not alone; it kind of makes you feel a little crazy when this happens over and over again. And I’m definitely not making any friends here as I’m pointing out these problems. I’ll go ahead and look for "zombie” see what others have come across.
There was a brief moment there where everything worked shortly after the original 2026 SketchUp release. But when everything else/other software and applications update, you’re kind of forced to start updating your operating system. So you update SketchUp as well, hoping that the bug fixes are all caught up. It’s almost as if the expectation is that you have a computer dedicated for SketchUp and nothing else…and you just leave it at it peak evolution. A shrine of 2024 if you will.
Wish this was taken more seriously by development.
“After updating to SketchUp 2026.1 and macOS Tahoe (26.2), SketchUp began hanging indefinitely with the UI unresponsive. The hang report shows the main AppKit event loop blocked by a Ruby timer callback (__CFRunLoopDoTimer → Ruby vm_exec_core), indicating a Ruby-driven background task running on the UI thread. SketchUp fails to recover, leaving the process alive but non-responsive for ~35 minutes. This behavior did not occur prior to the SketchUp and macOS Tahoe updates and strongly suggests a new interaction issue between SketchUp’s Ruby/CEF stack and Tahoe’s Cocoa event handling.”
What we know:
The hang report shows SketchUp frozen in the main AppKit event loop (NSApplication run) while executing a Ruby timer callback (CFRunLoopDoTimer → Ruby vm_exec_core). The UI thread is blocked for an extended period, which prevents SketchUp from processing events and makes it appear “Not Responding.” This behavior began only after updating to SketchUp 2026.1 and macOS Tahoe.
What has demonstrably changed:
The operating system is now less tolerant of blocking work inside UI-thread timer callbacks. Code paths that previously completed quickly no longer yield control back to the Cocoa event loop, resulting in a hard hang instead of a brief stall.
What we are inferring (but cannot prove from the log alone):
macOS Tahoe likely introduced changes in AppKit scheduling, run-loop timing, or process accounting that make blocking operations inside timers unsafe. SketchUp 2026.1 may also be interacting differently with Ruby timers or its embedded Chromium UI, amplifying the issue. We infer this because the same execution pattern existed before, but only fails under the new OS / SketchUp combination.
Bottom line:
Nothing “new” had to be added for this to break—updates changed the tolerance and timing of the UI event loop, exposing a pattern that previously worked but is no longer safe.
Interesting! I hadn’t thought to send a spin dump or crash report to AI for interpretation. The analysis seems consistent with behavior I have been coping with: on launch, SketchUp sometimes goes unresponsive while loading extensions. I have to force-quit, clean up the zombie, relaunch SketchUp without extensions loading, quit normally, then launch again but with extensions loading. This works maybe 90% of the time, but gets pretty tedious and annoying after a while.
My theory is that something burps while loading extensions and tries to display an html dialog to report the issue, maybe a problem “phoning home” for an extension license check. But by then CEF is fubar and SketchUp hangs.
The really disappointing thing is that AI could get that far but seemingly the devs could not.
Edit: it’s also possible, maybe likely, hat with the pending change from cocoa to Qt on Mac SketchUp, the devs have little time or interest in wrestling with cocoa-related problems.
The rumor I have heard is the SketchUp is going to build / replace the Mac UI since Cocoa is really old and breaking.
I understand that it wouldn’t make a lot of sense to invest time while you’re trying to kick out a better version…. But Mac folks are still paying the same amount as the Windows folks and many of us use it professionally every day all day. It’s more than a bummer and I would say.
It’s not a rumor. There is a mostly working port of Mac SketchUp to the Qt GUI library. It was demoed at bootcamp 2024. One can gain access by signing up to test it. The rumor is that it will be ready for release sometime in 2027.
