Unable to build apk (unable to find valid certification)

[mwasser04]

Question

I tried to build my flet app into an apk multiple times now.
Flutter SDK is installed and added to PATH
Android Studio is installed
Dont have Java installed, but as far as I know it is installed with Android Studio

Is there something i have to install first?

Code sample

No response

Error message

flet build apk
Creating Flutter bootstrap project...OK
Customizing app icons and splash images...OK
Generating app icons...OK
Generating splash screens...OK
Packaging Python app...OK
Building .apk for Android...Resolving dependencies...
  fl_chart 0.65.0 (0.66.2 available)
  flutter_lints 2.0.3 (3.0.1 available)
  flutter_native_splash 2.3.7 (2.3.13 available)
  js 0.6.7 (0.7.1 available)
  leak_tracker 10.0.0 (10.0.4 available)
  leak_tracker_flutter_testing 2.0.1 (3.0.3 available)
  leak_tracker_testing 2.0.1 (3.0.1 available)
  lints 2.1.1 (3.0.0 available)
  meta 1.11.0 (1.12.0 available)
  package_info_plus 4.2.0 (5.0.1 available)
  petitparser 5.4.0 (6.0.2 available)
  shared_preferences_web 2.2.1 (2.2.2 available)
  test_api 0.6.1 (0.7.0 available)
  toml 0.14.0 (0.15.0 available)
  url_launcher_web 2.2.0 (2.2.3 available)
  vm_service 13.0.0 (14.0.0 available)
  xml 6.3.0 (6.5.0 available)
Got dependencies!
17 packages have newer versions incompatible with dependency constraints.
Try `flutter pub outdated` for more information.

Running Gradle task 'assembleRelease'...
Running Gradle task 'assembleRelease'...                           896ms

Exception in thread "main" javax.net.ssl.SSLHandshakeException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested     
target
        at java.base/sun.security.ssl.Alert.createSSLException(Alert.java:131)
        at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:378)
        at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:321)
        at java.base/sun.security.ssl.TransportContext.fatal(TransportContext.java:316)
        at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:654)
        at java.base/sun.security.ssl.CertificateStatus$CertificateStatusConsumer.consume(CertificateStatus.java:293)
        at java.base/sun.security.ssl.SSLHandshake.consume(SSLHandshake.java:396)
        at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:480)
        at java.base/sun.security.ssl.HandshakeContext.dispatch(HandshakeContext.java:458)
        at java.base/sun.security.ssl.TransportContext.dispatch(TransportContext.java:201)
        at java.base/sun.security.ssl.SSLTransport.decode(SSLTransport.java:172)
        at java.base/sun.security.ssl.SSLSocketImpl.decode(SSLSocketImpl.java:1510)
        at java.base/sun.security.ssl.SSLSocketImpl.readHandshakeRecord(SSLSocketImpl.java:1425)
        at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:455)
        at java.base/sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:426)
        at java.base/sun.net.www.protocol.https.HttpsClient.afterConnect(HttpsClient.java:589)
        at java.base/sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:187)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream0(HttpURLConnection.java:1665)
        at java.base/sun.net.www.protocol.http.HttpURLConnection.getInputStream(HttpURLConnection.java:1589)
        at java.base/sun.net.www.protocol.https.HttpsURLConnectionImpl.getInputStream(HttpsURLConnectionImpl.java:224)
        at org.gradle.wrapper.Download.downloadInternal(Download.java:58)
        at org.gradle.wrapper.Download.download(Download.java:44)
        at org.gradle.wrapper.Install$1.call(Install.java:61)
        at org.gradle.wrapper.Install$1.call(Install.java:48)
        at org.gradle.wrapper.ExclusiveFileAccessManager.access(ExclusiveFileAccessManager.java:65)
        at org.gradle.wrapper.Install.createDist(Install.java:48)
        at org.gradle.wrapper.WrapperExecutor.execute(WrapperExecutor.java:128)
        at org.gradle.wrapper.GradleWrapperMain.main(GradleWrapperMain.java:61)
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target        
        at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:439)
        at java.base/sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:306)
        at java.base/sun.security.validator.Validator.validate(Validator.java:264)
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:231)
        at java.base/sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:132)
        at java.base/sun.security.ssl.CertificateMessage$T12CertificateConsumer.checkServerCerts(CertificateMessage.java:638)
        ... 23 more
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at java.base/sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:146)
        at java.base/sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:127)
        at java.base/java.security.cert.CertPathBuilder.build(CertPathBuilder.java:297)
        at java.base/sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:434)
        ... 28 more
Gradle task assembleRelease failed with exit code 1

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• I have searched for answers to my question both in the issues and in previous discussions.

[Mr-KAM]

@mwasser04 , please, what do you have as output with the command flutter doctor ?

[Mr-KAM]

You can try to upgrade your flet version by doing pip install --upgrade flet and retry after flet build apk --verbose .
You also have to add a requirements.txt file in your root folder and rename your script starting script file to main.py.

Just add required packages to your requirements.txt file and don't do it with pip freeze command. You can us pipreqs package instead.

[mwasser04]

flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.19.0, on Microsoft Windows [Version 10.0.22631.3155], locale de-DE)
[√] Windows Version (Installed version of Windows is version 10 or higher)
[√] Android toolchain - develop for Android devices (Android SDK version 34.0.0)
[X] Chrome - develop for the web (Cannot find Chrome executable at .\Google\Chrome\Application\chrome.exe)
    ! Cannot find Chrome. Try setting CHROME_EXECUTABLE to a Chrome executable.
[X] Visual Studio - develop Windows apps
    X Visual Studio not installed; this is necessary to develop Windows apps.
      Download at https://visualstudio.microsoft.com/downloads/.
      Please install the "Desktop development with C++" workload, including all of its default components
[√] Android Studio (version 2023.1)
[√] VS Code (version 1.86.2)
[√] Connected device (2 available)
[√] Network resources

! Doctor found issues in 2 categories.

[mwasser04]

Used pipreqs, output of flet build apk is still the same

this is the content of the requirements.txt:
flet==0.20.2

[Mr-KAM]

It seems like you don't have chrome chrome.exe and Visual Studio Visual studio installed. Try install this 2 apps and do flet build apk --verbose.

If you already have chrome installed check for update try setting environnement variable CHROME_EXECUTABLE to your Chrome executable file. The code for that should look like set CHROME_EXECUTABLE=C:\Program Files\Google\Chrome\Application\chrome.exe
or set CHROME_EXECUTABLE=path_to_chrome\chrome.exe if your chrome browser is installed in an other place