[v3] SystemTray updates can fatal the process

[johnmaguire]

Description

On Windows, a systray app that updates its tray menu via SystemTray.SetMenu() can fatally crash inside the Windows popup-menu build path.

I reproduced this on current upstream Wails: github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122

The fatal presents as:

time="2026-04-23T16:26:18-04:00" level=error msg="Fatal error in Wails application"
error="... error adding menu item 'Debug item 192 rebuild 246' ..."

and the stack is in the Windows tray/popup menu code, for example:

  goroutine 1 [running, locked to thread]:
  github.com/DefinedNet/dnclient/internal/ui.New.func3({0x7ff62d35c940, 0x400166ab88})
  	github.com/DefinedNet/dnclient/internal/ui/ui.go:92 +0x54
  github.com/wailsapp/wails/v3/pkg/application.(*App).handleError(0x4000634d00?, {0x7ff62d35c940?, 0x400166ab88?})
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application.go:445 +0x38
  github.com/wailsapp/wails/v3/pkg/application.(*App).handleFatalError(0x4000171408, {0x7ff62d35b4e0, 0x4000634d00})
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application.go:474 +0x70
  github.com/wailsapp/wails/v3/pkg/application.(*App).fatal(0x4000171408, {0x7ff62cff9f0e?, 0x4?}, {0x400063a450?, 0xe2961?, 0x0?})
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application.go:532 +0x4c
  github.com/wailsapp/wails/v3/pkg/application.(*Win32Menu).buildMenu(0x40000b2540, 0xe2961, 0x4000dfa8c0)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/popupmenu_windows.go:146 +0x5b4
  github.com/wailsapp/wails/v3/pkg/application.(*Win32Menu).Update(0x40000b2540)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/popupmenu_windows.go:167 +0x70
  github.com/wailsapp/wails/v3/pkg/application.NewPopupMenu(...)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/popupmenu_windows.go:179
  github.com/wailsapp/wails/v3/pkg/application.(*windowsSystemTray).updateMenu(0x4000380120, 0x4000dfa8c0)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray_windows.go:489 +0x98
  github.com/wailsapp/wails/v3/pkg/application.(*windowsSystemTray).setMenu(0x18?, 0x400063a628?)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray_windows.go:203 +0x1c
  github.com/wailsapp/wails/v3/pkg/application.(*SystemTray).SetMenu.func1()
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray.go:220 +0x28
  github.com/wailsapp/wails/v3/pkg/application.InvokeSync.func1()
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/mainthread.go:28 +0x44
  github.com/wailsapp/wails/v3/pkg/application.(*windowsApp).invokeCallback(0x40001541e0, 0x4000000121?, 0x2?)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/mainthread_windows.go:125 +0x298
  github.com/wailsapp/wails/v3/pkg/application.(*windowsApp).wndProc(0x0?, 0x400063a8e8?, 0x63a888?, 0x0?, 0x400063ab18?)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application_windows.go:232 +0x784
  syscall.SyscallN(0x0?, {0x4000231920?, 0x7ff62da25f40?, 0x7ff62c6cbd50?})
  	runtime/syscall_windows.go:500 +0x24
  syscall.(*Proc).Call(0x7ff62da25f20?, {0x4000231920?, 0x100ab2301?, 0x1f678940658?})
  	syscall/dll_windows.go:167 +0x24
  syscall.(*LazyProc).Call(0x7ff62da25f20, {0x4000231920, 0x6, 0x6})
  	syscall/dll_windows.go:287 +0x4c
  github.com/wailsapp/wails/v3/pkg/w32.TrackPopupMenuEx(...)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/w32/user32.go:973
  github.com/wailsapp/wails/v3/pkg/application.(*Win32Menu).ShowAt(0x40002d99e0, 0xa23, 0x690)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/popupmenu_windows.go:227 +0x264
  github.com/wailsapp/wails/v3/pkg/application.(*windowsSystemTray).openMenu(0x4000380120)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray_windows.go:66 +0x44
  github.com/wailsapp/wails/v3/pkg/application.InvokeSync.func1()
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/mainthread.go:28 +0x44
  github.com/wailsapp/wails/v3/pkg/application.(*App).dispatchOnMainThread(0x4000171408, 0x4000dbd290)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application.go:846 +0xcc
  github.com/wailsapp/wails/v3/pkg/application.InvokeSync(0x4000dbd278)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/mainthread.go:26 +0x8c
  github.com/wailsapp/wails/v3/pkg/application.(*SystemTray).OpenMenu(...)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray.go:368
  github.com/wailsapp/wails/v3/pkg/application.(*SystemTray).ShowMenu(...)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray.go:165
  github.com/wailsapp/wails/v3/pkg/application.(*windowsSystemTray).wndProc(0x4000380120, 0x401, 0x6a70a54, 0x10205)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/systemtray_windows.go:453 +0xe8
  github.com/wailsapp/wails/v3/pkg/application.(*windowsApp).wndProc(0x40001541e0, 0x80356, 0x401, 0x6a70a54, 0x10205)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application_windows.go:310 +0x598
  syscall.SyscallN(0x0?, {0x4000edd6e0?, 0x8?, 0x0?})
  	runtime/syscall_windows.go:500 +0x24
  syscall.(*Proc).Call(0x20?, {0x4000edd6e0?, 0x300187b01?, 0x7ff62cd1689c?})
  	syscall/dll_windows.go:167 +0x24
  syscall.(*LazyProc).Call(0x7ff62da23e60, {0x4000edd6e0, 0x4, 0x4})
  	syscall/dll_windows.go:287 +0x4c
  github.com/wailsapp/wails/v3/pkg/w32.GetMessage(...)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/w32/user32.go:466
  github.com/wailsapp/wails/v3/pkg/application.(*windowsApp).runMainLoop(0x40001541e0)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/mainthread_windows.go:62 +0x16c
  github.com/wailsapp/wails/v3/pkg/application.(*windowsApp).run(0x40001541e0)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application_windows.go:190 +0x33c
  github.com/wailsapp/wails/v3/pkg/application.(*App).Run(0x4000171408)
  	github.com/wailsapp/wails/v3@v3.0.0-alpha.78.0.20260422083913-b1fd8e9bd122/pkg/application/application.go:650 +0x6f8
  main.main()
  	github.com/DefinedNet/dnclient/cmd/dnclient-desktop/main.go:47 +0x668

To Reproduce

A minimal repro should be a Windows systray app that updates its tray menu frequently via SystemTray.SetMenu().

The pattern that reproduces for me is:

1. Create a Windows app with a SystemTray.
2. Build a tray menu with a few normal items, e.g. About, Quit, separators, and optionally some disabled items.
3. On a short timer, rebuild the menu and call SystemTray.SetMenu(newMenu).
4. After enough iterations, Wails fatally crashes in popupmenu_windows.go with error adding menu item '...'.

In my app, the menu was rebuilt from a background goroutine and handed to SystemTray.SetMenu() repeatedly.

Expected behaviour

SystemTray.SetMenu() should not fatally crash the process.

Screenshots

No response

Attempted Fixes

I have a PR incoming with fixes. The issue is related to resource leaks.

System Details

n/a

Additional context

No response

[github-actions]

👋 Thanks for reporting this issue! To help us investigate, could you please:

1. Add the output of wails doctor if not already included
2. Provide clear steps to reproduce the issue
3. If possible, create a minimal reproduction of the issue

This will help us resolve your issue much faster. Thank you!

[leaanthony]

Draft PR with fix and test: #5234

Changed fatal() to error() in buildMenu for both AppendMenu and SetMenuIcons failures, and added continue on AppendMenu failure. This matches the existing non-fatal handling of TrackPopupMenuEx failures. Needs runtime testing on Windows to confirm the fix.

[johnmaguire]

@leaanthony This fixes the proximal cause but not the root cause: resource leaks. Once we hit 10k resources we can no longer update the menu etc.

[johnmaguire]

In addition to the test harness demonstrating the issue in the PR I posted, this appears in our logs just prior the crash:

time="2026-04-18T23:03:34-04:00" level=error msg="failed to create systray dark mode icon: The current process has used all of its system allowance of handles for Window Manager objects." subsystem=ui

So far no crashes running the patch.

[johnmaguire]

We ran a burn-in test over the weekend to ensure the PR I posted (#5228) actually fixes the issue in a production scenario - it does. (i.e. running in our app, not the test harness.) We are running without the fatal->error change currently (but totally support this change as well.)