Fix Kivy App Crash on Android (Loading Screen Closes) – Buildozer Guide

Developing Android applications with Python frameworks such as Kivy and KivyMD has become increasingly popular. However, many developers face a frustrating issue: the application installs successfully, opens with a “Loading…” screen, and then suddenly closes.

This problem is very common when using Buildozer, and, in most cases, it is not caused by Buildozer itself but by issues in the application setup or code.

Understanding the Problem

When your app behaves like this:

• The APK installs successfully
• The app launches
• A “Loading…” screen appears
• The app closes immediately

It means the application has started but crashes during the initialization phase.

Main Causes (Fact-Checked)

Missing Dependencies (Most Common Cause)

If your code imports modules such as requests or uses KivyMD components, but they are not included in the buildozer.spec file, the app will crash instantly on Android.

Important:
Buildozer only packages the modules listed in the requirements section. Missing even one required module will cause a runtime crash.

KivyMD Version Compatibility

Certain widgets, such as MDLinearProgressIndicator, are only available in specific versions of KivyMD.

Important:
Using an incompatible version of KivyMD can cause the app to crash immediately after launch.

Heavy Operations During Startup

Running network requests or heavy logic inside the The build() method can lead to freezing or crashing, especially on slower devices or unstable internet connections.

Important:
Avoid executing API calls directly during app initialization.

File and Path Errors

If your app loads external files like .kv files or assets and they are not properly included in the APK, the app will fail at runtime.

Important:
Always ensure all required files are correctly packaged.

Silent Crashes (No Python Logs)

Sometimes the app crashes before Python logs are generated. In such cases, filtering logs using “python” will show nothing.

Important:
These crashes usually occur at the Android (Java/SDL) level and require full logcat inspection.

Step-by-Step Solution

Fix the buildozer.spec File

Ensure your requirements line is correct and includes all necessary dependencies:

requirements = python3,kivy,kivymd==1.1.1,requests

Important:
Using a stable version of KivyMD (such as 1.1.1) prevents compatibility issues.

Clean Previous Builds

buildozer android clean

This removes old cached builds that may cause conflicts.

Rebuild the Application

buildozer -v android debug

Deploy and Run

buildozer android deploy run

Debugging the Crash

If the app still crashes, use logcat to identify the issue.

Show only errors:

adb logcat *:E

Find crash details:

adb logcat | findstr "FATAL EXCEPTION"

Filter your app logs:

adb logcat | findstr bigsansarapp

Important:
Always analyze logcat output before guessing the issue.

Best Practice for Stable Apps

Avoid performing heavy operations during startup.

Incorrect approach:

def build(self):
    requests.get("https://api.example.com")

Correct approach:

from kivy.clock import Clock

def build(self):
    Clock.schedule_once(self.load_data, 1)

def load_data(self, dt):
    import requests
    requests.get("https://api.example.com")

Important:
Delaying execution prevents startup crashes and improves performance.

Practical Example

Here is a simple working example:

from kivymd.app import MDApp
from kivy.clock import Clock
from kivymd.uix.label import MDLabel
import requests

class TestApp(MDApp):
    def build(self):
        Clock.schedule_once(self.load_data, 1)
        return MDLabel(text="Loading...", halign="center")

    def load_data(self, dt):
        try:
            res = requests.get("https://jsonplaceholder.typicode.com/posts/1")
            print(res.json())
        except Exception as e:
            print("Error:", e)

TestApp().run()

If your app opens, shows a loading screen, and then closes, the issue is almost always related to:

• Missing dependencies
• Incorrect KivyMD version
• Improper startup logic

Important:
This is not a Buildozer problem. It is a configuration or code issue.