How to fix Google code scanner throwing "MlKitException: Failed to scan code"

Question

I have followed the tutorial here and got it work just fine. Then later, using the same code, I am getting this exception every time I try to open the QR code scanner:

com.google.mlkit.common.MlKitException: Failed to scan code.

I don't even leave my app, the exception is instantaneous.

It really bothers me on how this was working before and now it just doesn't work anymore.

Answer 1

I post my solution to these problem. This solve problem to barcore scann error:

Found in this guide: https://developers.google.com/android/guides/module-install-apis?hl=es-419

public void onScanButtonClicked() {

    GmsBarcodeScannerOptions.Builder optionsBuilder = new GmsBarcodeScannerOptions.Builder();
    if (allowManualInput) {
        optionsBuilder.allowManualInput();
    }
    if (enableAutoZoom) {
        optionsBuilder.enableAutoZoom();
    }

    ModuleInstallClient moduleInstallClient = ModuleInstall.getClient(getContext());

    OptionalModuleApi optionalModuleApi = GmsBarcodeScanning.getClient(getContext());
    moduleInstallClient
            .areModulesAvailable(optionalModuleApi)
            .addOnSuccessListener(
                    response -> {
                        if (response.areModulesAvailable()) {
                            // Modules are present on the device...
                            barcodeResultView.setText("Modules are present on the device");
                            GmsBarcodeScanner gmsBarcodeScanner = GmsBarcodeScanning.getClient(getContext(), optionsBuilder.build());
                            gmsBarcodeScanner
                                    .startScan()
                                    .addOnSuccessListener(barcode -> barcodeResultView.setText(getSuccessfulMessage(barcode)))
                                    .addOnFailureListener(
                                            e -> barcodeResultView.setText(getErrorMessage(e)))
                                    .addOnCanceledListener(
                                            () -> barcodeResultView.setText(getString(R.string.error_scanner_cancelled)));
                        } else {
                            // Modules are not present on the device...
                            barcodeResultView.setText("Modules are not present on the device");
                            moduleInstall();
                        }
                    })
            .addOnFailureListener(
                    e -> {
                        // Handle failure…
                        barcodeResultView.setText("Handle failure…");
                    });
}

final class ModuleInstallProgressListener implements InstallStatusListener {
    @Override
    public void onInstallStatusUpdated(ModuleInstallStatusUpdate update) {
        ModuleInstallStatusUpdate.ProgressInfo progressInfo = update.getProgressInfo();
        // Progress info is only set when modules are in the progress of downloading.
        if (progressInfo != null) {
            int progress =
                    (int) (progressInfo.getBytesDownloaded() * 100 / progressInfo.getTotalBytesToDownload());
            // Set the progress for the progress bar.
            progressBar.setProgress(progress);
        }
        // Handle failure status maybe…

        // Unregister listener when there are no more install status updates.
        if (isTerminateState(update.getInstallState())) {

            moduleInstallClient.unregisterListener(this);
        }
    }

    public boolean isTerminateState(@ModuleInstallStatusUpdate.InstallState int state) {
        return state == STATE_CANCELED || state == STATE_COMPLETED || state == STATE_FAILED;
    }
}

private void moduleInstall(){
    InstallStatusListener listener = new ModuleInstallProgressListener();

    OptionalModuleApi optionalModuleApi = GmsBarcodeScanning.getClient(getContext());
    ModuleInstallRequest moduleInstallRequest =
            ModuleInstallRequest.newBuilder()
                    .addApi(optionalModuleApi)
                    // Add more API if you would like to request multiple optional modules
                    //.addApi(...)
                    // Set the listener if you need to monitor the download progress
                    .setListener(listener)
                    .build();

    moduleInstallClient.installModules(moduleInstallRequest)
            .addOnSuccessListener(
                    response -> {
                        if (response.areModulesAlreadyInstalled()) {
                            // Modules are already installed when the request is sent.
                            barcodeResultView.setText("Modules are already installed when the request is sent.");
                        }
                    })
            .addOnFailureListener(
                    e -> {
                        // Handle failure...
                        barcodeResultView.setText(getErrorMessage(e));
                    });

}