How to Write Report When App Crash?

[KiddoV]

How do I write a report to, says text (.txt) file, if my complied app (.exe) crash?

In other words, simply write all logs to a file, when app crashed.

Thanks,

[ecsdantas]

You can create a function Init to set the default output log as:

func Init(){
	logpath := "C:\\MyLogFile.log"
	flog, err = os.OpenFile(logpath, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0777)
	log.SetFlags(3)
	log.SetOutput(flog)
}

After that, just use log.Println("information") and log.Panic(err) where you want.

[leaanthony]

Open a ticket for a crash reporter. It'll be a function option that receives an error. We can then write a top level recover method that will call this option if available

[KiddoV]

Any update on this... "feature"? Maybe in V3? 🤔

Or maybe something like this?.

app := NewApp()

err := wails.Run(&options.App{
    [...]
    OnCrash: app.onCrash, // Call on app crash or before it crash? (I mean PANIC or FATAL)
})

Sorry I forgot to open the ticket, I was out of the loop, not sure if this feature added?

[RichardLindhout]

@leaanthony does this work in v3?

[RichardLindhout]

I did do this the following way now

I created a package crashdialog

// crashdialog_darwin.go
//go:build darwin
// +build darwin

package crashdialog

import (
	"fmt"
	"os/exec"
)

// ShowCrashDialog displays a native dialog on macOS with the crash report inside a text input for easy copying.
func ShowCrashDialog(crashReport string) error {
	appleScript := fmt.Sprintf(`
		tell application "System Events"
			display dialog "The app has crashed. Please copy the crash report below and send it to support@webridge.nl:" default answer "%s" buttons {"OK"} default button "OK" with icon caution
		end tell`, crashReport)

	cmd := exec.Command("osascript", "-e", appleScript)
	return cmd.Run()
}

windows

// crashdialog_windows.go
//go:build windows
// +build windows

package crashdialog

import (
	"fmt"
	"log"
	"syscall"
	"unsafe"
)

var (
	user32          = syscall.NewLazyDLL("user32.dll")
	procMessageBoxW = user32.NewProc("MessageBoxW")
)

const (
	MB_ICONERROR = 0x00000010
	MB_OK        = 0x00000000
)

// ShowCrashDialog displays a simple native MessageBox with the crash report.
func ShowCrashDialog(crashReport string) error {
	message := fmt.Sprintf("The app has crashed. Please copy the crash report below and send it to support@webridge.nl:\n\n%s", crashReport)
	title := "App Crash"

	// Windows native MessageBox (without text input but keeps it very simple)
	t, _ := syscall.UTF16PtrFromString(title)
	c, _ := syscall.UTF16PtrFromString(message)

	// Call MessageBoxW from user32.dll
	ret, _, _ := procMessageBoxW.Call(0, uintptr(unsafe.Pointer(c)), uintptr(unsafe.Pointer(t)), MB_ICONERROR|MB_OK)
	if ret == 0 {
		log.Printf("Failed to show dialog")
		return fmt.Errorf("failed to show dialog")
	}
	return nil
}

func panicHandler(output string) {
	if err := crashdialog.ShowCrashDialog(output); err != nil {
		log.Error().Err(err).Msg("Failed to show crashdialog dialog")
	}
}

func main() {
	exitStatus, err := panicwrap.BasicWrap(panicHandler)
	if err != nil {
		// Something went wrong setting up the panic wrapper. Unlikely,
		// but possible.
		panic(err)
	}

	// If exitStatus >= 0, then we're the parent process and the panicwrap
	// re-executed ourselves and completed. Just exit with the proper status.
	if exitStatus >= 0 {
		os.Exit(exitStatus)
	}

	app := NewApp()

[KiddoV]

I assumed you are using "github.com/mitchellh/panicwrap"?

[RichardLindhout]

Hmmm. This still does silently crash without the alert. I don't know why it does..

[lysShub]

windows, set windows.SetStdHandle at start

[COD3HUNT3R]

Maybe Sentry(sentry.io) could be an option.

[leaanthony]

Great solutions shared here — thanks everyone for contributing workarounds!

To summarize what works today:

For file-based logging before a crash, the log.SetOutput(file) approach shared above is reliable for capturing pre-crash output.

For panic/crash detection with a user-facing dialog, @RichardLindhout's panicwrap-based approach is the most complete community solution. The silent crash issue likely comes from the panic happening before the wrapper process has a chance to intercept it — make sure panicwrap.BasicWrap is the very first thing in main(), before any Wails or application initialization.

v3 note: A first-class crash reporter option (a function hook that fires on unhandled panics) has been requested — please 👍 the feature request if you want it prioritized. In the meantime the panicwrap approach works for both v2 and v3.

If the silent crash issue persists after putting BasicWrap first, please open a separate issue with a minimal reproducer — happy to dig in.