Troubleshoot PWA Wrapper

Last modified: July 23, 2026

Introduction

This page describes known issues you may encounter when building or testing PWA Wrapper apps, along with the steps to resolve them.

Android

App Cannot Connect to localhost on a Physical Device

  • Symptom — When you set the runtime URL to a localhost address (for example, http://localhost:8080) and install the app on a physical Android device, the app fails to load and shows the following error:

    Page Load Error
net::ERR_CACHE_MISS
    Page Load Error showing net::ERR_CACHE_MISS on Android

  • Cause — Two things are required for a physical Android device to reach a localhost server on your machine:

    • The app must have the INTERNET permission. Without it, the Android OS blocks all outbound network traffic.
    • The device must have a port forwarding rule from its own localhost to your machine's localhost. Android devices do not forward ports automatically.

  • Solution — To solve this issue, do the following:

  1. In the PWA Wrapper builder, go to the Permissions step and enable the INTERNET permission (for general guidance on permissions, see Build PWA Wrapper Apps).

  2. Connect the Android device to your machine via USB and make sure USB debugging is enabled on the device.

  3. Run the following ADB command to forward port 8080 from the device to your machine:

    adb reverse tcp:8080 tcp:8080

    If your Mendix runtime uses a different port, replace 8080 with the correct port number on both sides.

  4. Rebuild and reinstall the app with the localhost runtime URL.

The app can now reach the Mendix runtime running on your development machine.