[BUG] App not responding on MacOS after update

[OliverRC]

Describe the bug

The App opens and freezes completely after update. Tried uninstalling it and doing a fresh install and it still freezes.

Reproduction steps

1. Open latest version on MacOs
2. It opens ... freezes

Expected behavior

Should not freeze

Actual behavior

Freezes

App Version

1.6.4 (15)

macOS Version

macOS 26.5.1 (Build 25F80)

Architecture

Apple Silicon

Logs or crash report

Heaviest stack for the main thread of the target process:
  11  <truncated backtrace>
  11  kevent_id + 8 (libsystem_kernel.dylib + 10868) [0x18e7a3a74]
 *11  ??? (kernel.release.t6041 + 6031544) [0xfffffe000bcf48b8]


Process:          FluidVoice [70123] [unique pid 1063016]
UUID:             7B797F41-1274-332F-A67B-A0015D07E662
Path:             /Applications/FluidVoice.app/Contents/MacOS/FluidVoice
Identifier:       com.FluidApp.app
Version:          1.6.4 (15)
Team ID:          V4J43B279J
Is First Party:   No
Beta Identifier:  4F9A96DC-1293-53D4-82F3-DCAC75F0CF78
Shared Cache:     FF7119A7-F64D-305D-8135-7E6EB1C207D1 slid base address 0x18e2f4000, slide 0xe2f4000 (System Primary)
Architecture:     arm64
Memory Limit:     0MB
Jetsam Priority:  100
Footprint:        94.80 MB
Time Since Fork:  63s
Num samples:      11 (1-11)
CPU Time:         0.002s (6.3M cycles, 4.5M instructions, 1.41c/i, 2.65GHz avg)
Num threads:      13
Note:             3 idle work queue threads omitted

  Thread 0xcd410e    11 samples (1-11)    priority 46 (base 46)    last ran 47.784s ago
  <thread QoS user interactive (requested user interactive), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  kevent_id + 8 (libsystem_kernel.dylib + 10868) [0x18e7a3a74] 1-11
     *11  ??? (kernel.release.t6041 + 6031544) [0xfffffe000bcf48b8] (blocked by turnstile with priority 47 waiting for FluidVoice [70123] [unique pid 1063016] thread 0xcd437a) 1-11

  Thread 0xcd4245    Thread name "com.apple.NSEventThread"    11 samples (1-11)    priority 46 (base 46)    cpu time <0.001s (2.4M cycles, 1537.5K instructions, 1.54c/i, 2.59GHz avg)
  <thread QoS user interactive (requested user interactive), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  thread_start + 8 (libsystem_pthread.dylib + 7196) [0x18e7e0c1c] 1-11
    11  _pthread_start + 136 (libsystem_pthread.dylib + 27736) [0x18e7e5c58] 1-11
      11  _NSEventThread + 184 (AppKit + 1420412) [0x192df1c7c] 1-11
        11  _CFRunLoopRunSpecificWithOptions + 532 (CoreFoundation + 1372612) [0x18e9741c4] 1-11
          11  __CFRunLoopRun + 1188 (CoreFoundation + 510404) [0x18e8a19c4] 1-11
            11  __CFRunLoopServiceMachPort + 160 (CoreFoundation + 516312) [0x18e8a30d8] 1-11
              11  mach_msg + 24 (libsystem_kernel.dylib + 4032) [0x18e7a1fc0] 1-11
                11  mach_msg_overwrite + 480 (libsystem_kernel.dylib + 39360) [0x18e7aa9c0] 1-11
                  11  mach_msg2_trap + 8 (libsystem_kernel.dylib + 3124) [0x18e7a1c34] 1-11
                   *11  ??? (kernel.release.t6041 + 206244) [0xfffffe000b7665a4] 1-11

  Thread 0xcd4231    1 sample (7)    priority 31 (base 31)    cpu time <0.001s (1399.0K cycles, 1031.6K instructions, 1.36c/i, 2.59GHz avg)
  <Thread in another call tree for 6 samples, thread QoS default (requested default), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  1  start_wqthread + 8 (libsystem_pthread.dylib + 7184) [0x18e7e0c10] 7
    1  __workq_kernreturn + 8 (libsystem_kernel.dylib + 10736) [0x18e7a39f0] 7
     *1  ??? (kernel.release.t6041 + 5849500) [0xfffffe000bcc819c] (runnable) 7

  Thread 0xcd4392    Thread name "ANEServicesThread"    11 samples (1-11)    priority 58 (base 58)    last ran 51.639s ago
  <process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  mach_msg2_trap + 8 (libsystem_kernel.dylib + 3124) [0x18e7a1c34] 1-11
     *11  ??? (kernel.release.t6041 + 206244) [0xfffffe000b7665a4] 1-11

  Thread 0xcd424e    Thread name "caulk.messenger.shared:high"    11 samples (1-11)    priority 55 (base 55)    last ran 57.571s ago
  <process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  semaphore_wait_trap + 8 (libsystem_kernel.dylib + 2992) [0x18e7a1bb0] 1-11
     *11  ??? (kernel.release.t6041 + 666804) [0xfffffe000b7d6cb4] 1-11

  Thread 0xcd437a    11 samples (1-11)    priority 47 (base 47)    last ran 47.805s ago
  <thread QoS user interactive (requested default, promote user interactive, workloop servicer override default), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  __psynch_cvwait + 8 (libsystem_kernel.dylib + 17676) [0x18e7a550c] 1-11
     *11  psynch_cvcontinue + 0 (pthread + 17948) [0xfffffe000b6739ac] 1-11

  Thread 0xcd4371    Thread name "com.apple.audio.toolbox.AUScheduledParameterRefresher"    11 samples (1-11)    priority 37 (base 37)    last ran 47.816s ago
  <thread QoS user initiated (requested user initiated), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  semaphore_wait_trap + 8 (libsystem_kernel.dylib + 2992) [0x18e7a1bb0] 1-11
     *11  ??? (kernel.release.t6041 + 666804) [0xfffffe000b7d6cb4] 1-11

  Thread 0xcd4372    Thread name "caulk::deferred_logger"    11 samples (1-11)    priority 37 (base 37)    last ran 57.571s ago
  <thread QoS user initiated (requested user initiated), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  semaphore_wait_trap + 8 (libsystem_kernel.dylib + 2992) [0x18e7a1bb0] 1-11
     *11  ??? (kernel.release.t6041 + 666804) [0xfffffe000b7d6cb4] 1-11

  Thread 0xcd438f    11 samples (1-11)    priority 31 (base 31)    last ran 47.620s ago
  <thread QoS default (requested default, workloop servicer override default), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  __psynch_cvwait + 8 (libsystem_kernel.dylib + 17676) [0x18e7a550c] 1-11
     *11  psynch_cvcontinue + 0 (pthread + 17948) [0xfffffe000b6739ac] 1-11

  Thread 0xcd4b45    Thread name "com.apple.NSURLConnectionLoader"    11 samples (1-11)    priority 31 (base 31)    last ran 27.638s ago
  <thread QoS default (requested default), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 0>
  11  <truncated backtrace> 1-11
    11  mach_msg2_trap + 8 (libsystem_kernel.dylib + 3124) [0x18e7a1c34] 1-11
     *11  ??? (kernel.release.t6041 + 206244) [0xfffffe000b7665a4] 1-11

  Thread 0xcd424d    Thread name "caulk.messenger.shared:17"    11 samples (1-11)    priority 19 (base 19)    last ran 59.466s ago
  <thread QoS utility (requested utility), process unclamped, jetsam priority 100 (requested 100, assertion 0), process memory limit 0MB, process received importance donation from WindowServer [403], process received importance donation from coreaudiod [423], process received importance donation from CursorUIViewService [838], IO tier 1>
  11  <truncated backtrace> 1-11
    11  semaphore_wait_trap + 8 (libsystem_kernel.dylib + 2992) [0x18e7a1bb0] 1-11
     *11  ??? (kernel.release.t6041 + 666804) [0xfffffe000b7d6cb4] 1-11

  Binary Images:
           0x100b4c000 -        0x101d4bfff  com.FluidApp.app 1.6.4 (15)             <7B797F41-1274-332F-A67B-A0015D07E662>             /Applications/FluidVoice.app/Contents/MacOS/FluidVoice
           0x18e7a1000 -        0x18e7de2af  libsystem_kernel.dylib (12377.121.6)    <CC1CF985-BC65-3725-809F-4C1E36B8F4BA>             /usr/lib/system/libsystem_kernel.dylib
           0x18e7df000 -        0x18e7ebb3b  libsystem_pthread.dylib (539.100.4)     <4F33683C-18C8-39A1-800B-2E3BD43BCC13>             /usr/lib/system/libsystem_pthread.dylib
           0x18e825000 -        0x18ed8331f  com.apple.CoreFoundation 6.9 (5026.5.4) <04E3598B-F226-3250-B3B2-CE938DD4DB7E>             /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation
           0x192c97000 -        0x1943b9f9f  com.apple.AppKit 6.9 (2685.60.104)      <CF57A4FC-4BE3-3D95-B543-D744E8718B26>             /System/Library/Frameworks/AppKit.framework/Versions/C/AppKit
   *0xfffffe000b66f390 - 0xfffffe000b674f8f  com.apple.kec.pthread (1)               <89A0C193-9EB4-31CC-9153-31B9685406A7>__TEXT_EXEC  /System/Library/Extensions/pthread.kext/Contents/MacOS/pthread
   *0xfffffe000b734000 - 0xfffffe000c09bfff  kernel.release.t6041 (25.5.0)           <F2125215-7A32-331D-9F8E-0103F561CA91>__TEXT_EXEC  /System/Library/Kernels/kernel.release.t6041

Screenshots or screen recording

No response

[devzahirul]

I dug into the spindump — the freeze signature is readable even with the truncated frames: the main thread is parked in kevent_id (a dispatch workloop sync-wait) and the kernel turnstile says it's blocked on another FluidVoice thread (0xcd437a) that is itself stuck forever in psynch_cvwait, with a second worker also in a condition wait and every CoreAudio thread going idle at the same moment (~15s after launch).

That points at the idle route-change path in 1.6.4: when a route change arrives while the app is idle, the prewarmed AVAudioEngine is retired — its dealloc now always drains on a background queue — and the replacement engine is built on the main thread immediately, while that teardown is still in flight. Both engines' teardown and bring-up serialize inside CoreAudio's HAL, and if they interleave badly the main thread parks behind the wedged teardown permanently. Route changes fire in bursts right after launch (Bluetooth reconnecting, default device settling), which is why it presents as "opens … freezes" and survives a reinstall.

Opened #621, which sequences the rebuild strictly after the retired engine has finished deallocating (serial drain queue + completion), coalesces route-change bursts, and applies the same ordering to mid-recording recovery with a bounded wait. Verified live by programmatically flipping the default output device with the app idle — the rebuild now lands ~30ms after the drain instead of overlapping it, and the app stays responsive across repeated changes.

@OliverRC if you're able to attach the full spindump (spindump FluidVoice -o ~/Desktop/fluidvoice-spindump.txt while it's frozen), the untruncated frames would confirm the exact wedge point — but the fix removes this overlap either way.

[DorjeDorf]

Just hit the same. Even downgrading to 1.6.3 does not fix the issue.

[duncanmapes]

same... works a bit then crashes hard... thought it was due to bluetooth mic, but usb mic is the same

[DorjeDorf]

Going back to 1.6.2 worked for me to get the app back. In my case, 1.6.4 and 1.6.3 wouldn't even start. 1.6.2 did start, but I had to reconfigure the local AI refinement model settings.

[altic-dev]

Turn off experimental option on bototm of settings to see if it helps for now.

I merged the change from @devzahirul - is this still the race condition - any idea?

[duncanmapes]

Turn off experimental option on bototm of settings to see if it helps for now.

I merged the change from @devzahirul - is this still the race condition - any idea?

no help... 1.6.2 doesn't work for me either

[OliverRC]

It seems related to input devices. If I switch or change inputs the app dies. The experimental settings are all off, I never had them on.

[Zoolander1987]

I've got the same issue since the last release.
Expertimental settings are off. And going back to 1.6.2 doesn't work for me either.

[devzahirul]

Update after reviewing the newer reports and the release history:

The Bluetooth/external-input clue strongly reinforces the CoreAudio route-change deadlock. The #620 spindump is a hang, not a conventional crash: the main thread is parked in kevent_id waiting on another FluidVoice thread, while that worker is parked in psynch_cvwait. This matches the lower-level signature from #542, where the full symbolicated sample proved the circular wait:

• main thread: AVAudioEngine retirement/dealloc synchronously waits for the engine internal queue
• engine queue: AVAudioEngineConfigurationChange delivery waits for its observer on the main queue

Bluetooth, USB, display, aggregate, and Continuity audio devices are triggers because connecting or switching them can emit default-input, default-output, device-list, and engine-configuration changes in a burst. FluidVoice registers those listeners and prewarms AVAudioEngine at startup, so a route settling immediately after launch can present as opens, then freezes.

Importantly, the reports on 1.6.2, 1.6.3, and 1.6.4 do not test the merged #542 fix. The v1.6.4 tag, 6174aa7, was cut before PR #543 was merged as 724be13. All three released versions still contain the vulnerable queue: .main observer and retirement handoff. Therefore downgrading to 1.6.2 not helping is expected and strengthens the #542 diagnosis; it does not invalidate it. Reinstalling also leaves the same code and CoreAudio device topology in place.

Experimental capture being off does not avoid this path. With it off, FluidVoice uses the AVAudioEngine compatibility backend directly.

PR #543 breaks both legs of the confirmed circular wait. PR #621 addresses an additional real hazard: old-engine teardown overlapping successor-engine bring-up inside the HAL. The truncated #620 frames cannot distinguish those two mechanisms, so I would treat #543 as the confirmed hotfix and #621 as complementary lifecycle hardening.

Recommended validation: give affected reporters a signed build containing 724be13 or later, then repeat launch and input switching with Bluetooth/USB devices. If it still hangs, please capture a full sample or spindump from that build; the untruncated frames will show whether any remaining wait is teardown/bring-up overlap rather than the already-fixed NotificationCenter cycle.