Android Wi-Fi Direct hotspot failure

Question

I'm new to the Android platform and I want to create an app that creates a wi-fi hotspot so my microcontroller (esp32-c3) can connect to it. Further, the app should only contain a webview and be able to automatically determinate the IP-adres of the microcontroller so there can be established a Websocket connection to receive sensor data.

After much frustration setting up the IDE, I finally managed to build a simple app and and run it on my phone. My problem is that I always get a failure with reason code 0 (WifiP2pManager.ERROR) after creating a group, which is according to the documentation an internal error. I've tested this on multiple phones (Android 12 and 13) with the same result.

What I noticed is that there are barley examples available covering this topic. Am i making a mistake and is it possible to find out the detailed error message instead of seeing just htis generic error code?

This whole platform is difficult and frustrating. Can someone help me out? It must definitely be possible to create this on my phone, because with the app PdaNet+ I'm able to create a wi-fi direct hotpot that works.

public class MainActivity extends AppCompatActivity implements WifiP2pManager.ChannelListener, WifiP2pManager.ActionListener {
    private final IntentFilter intentFilter = new IntentFilter();
    private TextView tv1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tv1 = this.findViewById(R.id.tv1);

        intentFilter.addAction(WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION);
        intentFilter.addAction(WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION);

        WifiP2pManager manager = (WifiP2pManager) getSystemService(Context.WIFI_P2P_SERVICE);
        WifiP2pManager.Channel channel = manager.initialize(this, getMainLooper(), this);
        manager.createGroup(channel, this);

        BroadcastReceiver receiver = new BroadcastReceiver() {
            @Override
            public void onReceive(Context context, Intent intent) {
                String action = intent.getAction();
                tv1.append("\n" + action);
                if (WifiP2pManager.WIFI_P2P_STATE_CHANGED_ACTION.equals(action)) {
                    int state = intent.getIntExtra(WifiP2pManager.EXTRA_WIFI_STATE, -1);
                    if (state == WifiP2pManager.WIFI_P2P_STATE_ENABLED) {
                        tv1.append("\nWifi P2P is enabled");
                    } else {
                        tv1.append("\nWifi P2P is disabled");
                    }
                } else if (WifiP2pManager.WIFI_P2P_PEERS_CHANGED_ACTION.equals(action)) {
                    tv1.append("\nCall WifiP2pManager.requestPeers() to get a list of current peers");
                } else if (WifiP2pManager.WIFI_P2P_CONNECTION_CHANGED_ACTION.equals(action)) {
                    tv1.append("\nRespond to new connection or disconnections");
                } else if (WifiP2pManager.WIFI_P2P_THIS_DEVICE_CHANGED_ACTION.equals(action)) {
                    tv1.append("\nRespond to this device's wifi state changing");
                }
            }
        };
        registerReceiver(receiver, intentFilter);
    }

    @Override
    public void onSuccess() {
        tv1.append("\nGroup created successfully");
    }

    @Override
    public void onFailure(int reason) {
        tv1.append("\nFailed to create group (reason "+reason+")");
    }

    @Override
    public void onChannelDisconnected() {
        tv1.append("\nonChannelDisconnected");
    }
}

Manifest:

    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_MULTICAST_STATE" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
    <uses-permission android:name="android.permission.CHANGE_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.NEARBY_WIFI_DEVICES" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

Answer 1

I finally solved the problem: it turned out the location permission was blocked. After giving access, the hotspot could get created.