Summary
On an Android emulator, mobile_launch_app fails for valid, installed apps with "Failed launching app with package name … please make sure it exists". The package exists and is launchable — the problem is that launchApp runs adb shell monkey -c LAUNCHER and treats monkey's non-zero exit code as a launch failure, but monkey returns non-zero here even when the package is fine.
Environment
|
|
| mobile-mcp |
0.0.59 |
| Device |
Pixel 7 API 33 emulator, Android 13 |
| adb |
1.0.41 |
| Host |
macOS 26.5.1 (arm64), Node v25.9.0 |
Reproduction
mobile_list_apps({device}) -> includes com.android.settings, com.android.chrome
mobile_launch_app({device, packageName: "com.android.settings"})
-> "Failed launching app with package name \"com.android.settings\", please make sure it exists"
mobile_launch_app({device, packageName: "com.android.chrome"})
-> same failure
Both are installed and launchable.
Root cause
lib/android.js launchApp():
try {
this.silentAdb("shell", "monkey", "-p", packageName, "-c", "android.intent.category.LAUNCHER", "1");
} catch (error) {
throw new ActionableError(`Failed launching app with package name "${packageName}", please make sure it exists`);
}silentAdb uses execFileSync, which throws on any non-zero exit code. On this emulator image, monkey -c LAUNCHER exits non-zero even for valid packages:
$ adb shell monkey -p com.android.settings -c android.intent.category.LAUNCHER 1 ; echo "exit=$?"
...
** SYS_KEYS has no physical keys but with factor 2.0%.
exit=251
Meanwhile the package clearly resolves a LAUNCHER activity and am start launches it fine:
$ adb shell cmd package resolve-activity --brief com.android.settings
com.android.settings/.Settings
$ adb shell am start -n com.android.settings/.Settings ; echo "exit=$?"
Starting: Intent { cmp=com.android.settings/.Settings }
exit=0
So monkey's exit code is an unreliable success signal, and launchApp is gated on it.
Suggested fix
Any of:
- Don't treat
monkey's non-zero exit as fatal (it returns non-zero for benign reasons); check whether the app actually came to the foreground instead.
- Resolve the launcher activity via
adb shell cmd package resolve-activity --brief <pkg> and launch with adb shell am start -n <pkg>/<activity> (exit code is reliable).
- Fall back to
am start when monkey returns non-zero.
mobile_open_url already uses the more robust am start -a android.intent.action.VIEW and works reliably, which supports moving launchApp to am start.
Happy to test a patch — repro is consistent here.
Summary
On an Android emulator,
mobile_launch_appfails for valid, installed apps with "Failed launching app with package name … please make sure it exists". The package exists and is launchable — the problem is thatlaunchApprunsadb shell monkey -c LAUNCHERand treats monkey's non-zero exit code as a launch failure, butmonkeyreturns non-zero here even when the package is fine.Environment
0.0.59Reproduction
Both are installed and launchable.
Root cause
lib/android.jslaunchApp():silentAdbusesexecFileSync, which throws on any non-zero exit code. On this emulator image,monkey -c LAUNCHERexits non-zero even for valid packages:Meanwhile the package clearly resolves a LAUNCHER activity and
am startlaunches it fine:So
monkey's exit code is an unreliable success signal, andlaunchAppis gated on it.Suggested fix
Any of:
monkey's non-zero exit as fatal (it returns non-zero for benign reasons); check whether the app actually came to the foreground instead.adb shell cmd package resolve-activity --brief <pkg>and launch withadb shell am start -n <pkg>/<activity>(exit code is reliable).am startwhenmonkeyreturns non-zero.mobile_open_urlalready uses the more robustam start -a android.intent.action.VIEWand works reliably, which supports movinglaunchApptoam start.Happy to test a patch — repro is consistent here.