AltTab crashes on macOS 12.3

[alt-tab-macos-bot]

This issue was opened by a bot after a user submitted feedback through the in-app form.

Message:

Alt-tab seems to be crashing on Monterey public beta 12.3 (21E5196i)

Debug profile

• App version: 6.29.0
• App preferences:
  • MSAppCenter310AppCenterUserDefaultsMigratedKey: 1
  • MSAppCenter310CrashesUserDefaultsMigratedKey: 1
  • MSAppCenterInstallId: 936F6CB1-C59B-4312-8AAF-DB444C54A48C
  • MSAppCenterNetworkRequestsAllowed: 0
  • MSAppCenterPastDevices: {length = 1153, bytes = 0x62706c69 73743030 d4010203 04050607 ... 00000000 0000038d }
  • MSAppCenterSessionIdHistory: {length = 460, bytes = 0x62706c69 73743030 d4010203 04050607 ... 00000000 00000156 }
  • MSAppCenterUserIdHistory: {length = 455, bytes = 0x62706c69 73743030 d4010203 04050607 ... 00000000 00000151 }
  • NSStatusItem Preferred Position Item-0: 898
  • NSWindow Frame NSFontPanel: 1281 115 445 232 0 0 1792 1095
  • SUHasLaunchedBefore: 1
  • SULastCheckTime: 2022-01-24 22:59:20 +0000
  • alignThumbnails: 1
  • appsToShow: 0
  • crashPolicy: 0
  • fadeOutAnimation: false
  • hideWindowlessApps: false
  • holdShortcut: ⌘
  • holdShortcut2: ⌥
  • mouseHoverEnabled: false
  • nextWindowShortcut2: ⇥
  • preferencesVersion: 6.29.0
  • showTabsAsWindows: false
  • spacesToShow: 1
  • spacesToShow2: 1
  • updatePolicy: 1
  • windowMaxWidthInRow: 30
• Applications: 63
• Windows: 7
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: true, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
  • {isFullscreen: false, isWindowlessApp: true, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 18446744073709551615, spaceIndex: 9223372036854775807}
  • {isFullscreen: false, isWindowlessApp: false, isMinimized: false, isHidden: false, isTabbed: false, isOnAllSpaces: false, shouldShowTheUser: true, spaceId: 1, spaceIndex: 1}
• OS version: Version 12.3 (Build 21E5196i)
• OS architecture: x86_64
• Locale: en_DK (current)
• Spaces: 2
• Dark mode: Dark
• "Displays have separate Spaces": checked
• Hardware model: MacBookPro16,1
• Screens: 1
  • {x: 0.0, y: 0.0, width: 1792.0, height: 1120.0}
• CPU model: Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
• Memory size: 17,18 GB
• Active CPU count: 16
• Current CPU frequency: 2.3 Ghz
• Resource utilization:
  • CPU: 0.0%
  • Memory: 81M
  • Threads count: 16

[lwouis]

I'm observing a spike in crashes in AppCenter (from people voluntarily sending crash reports):

The worrisome thing is that it seems to happen in the screenshot method, which calls CGSHWCaptureWindowList. This is the private API we use to get screenshots of windows with good performance. The public API which does it is way slower, and also doesn't work in some cases (maybe windows on other Spaces, I'm not remembering in details).

If Apple pulled that private API away, it's bad news.

[Eugleo]

I'm at 12.3 and AltTab works for a while before crashing. The window previews also work alright. I don't know the inner workings of AltTab, but I guess this hints at some other problem than a non-existent API?

.

[rick-yao]

this is fixed by 12.3 beta2 , FYI

[kylemart]

Ended up uninstalling AltTab because I couldn't get it to stop crashing and re-launching -- rinse and repeat. Currently on the 21E5196i beta build, but once I receive the 21E5206e beta build I'll re-install AltTab and share my findings. Thanks for the info @rick-yao :)

[kylemart]

Can confirm that this is resolved after updating to the second 12.3 beta build (21E5206e).

[stevetodd]

The new ScreenCaptureKit looks like it might be useful for AltTab moving forward:
https://developer.apple.com/documentation/screencapturekit

Apple working on this might be destabilizing these private APIs.

[lwouis]

There is already an API for this kind of stuff on macOS. I'm not sure why they are making a new one instead of updating the existing one.

This is interesting and related to #122

[Gadagadanagadanagana]

I'm on 12.3.1, still crashing for me after a few minutes of working with AltTab. It's a pity that this little gem is not working properly.

[Filaipus]

It was working fine the first day I installed it but after a computer restart it just crashes (in my case it freezes up, like it's trying to process but it is stuck somewhere. It only does this once I actually use it, if I never go to the "windows screen" I can change settings and all that without issue).
Also on 12.3.1

Any logs or anything I can share here that would help?

[lwouis]

It's been a while since i removed the launchd flag that would relaunch AltTab if crashed. That should take care of the aggressive relaunch loop issue.

I'll close this ticket because nothing here is actionable. I track crashes, not only macOS 12.3, on AppCenter, when people send crash reports. So please click send if it crashes for you. With enough reports, i usually find a fix.

These days there are very few crashes though