Unable to log in to Proton Mail app on FP6+ Murena

# Bug Report : Unable to log in to Proton Mail app on FP6+ Murena

## Summary

Proton Mail app shows “Login credentials are incorrect” on Fairphone 6+ Murena, while the same login works perfectly on Fairphone 6 Murena and iPad.

## Environment

- **Device**: Fairphone 6+ (Snapdragon 7s Gen 4, 12 GB RAM)

- **ROM**: Murena /e/OS

- **Application**: Proton Mail v7.11.5 (August 27, 2026)

- **DNS**: Quad9 (also works on FP6 with Quad9)

## Problem Details

- Error message: “The login credentials are not correct. We invite you to try again.”

- Same account/password works flawlessly on:

  • Fairphone 6 (Snapdragon 7s Gen 3, 8 GB RAM) with Murena

  • iPad (iOS)

## Troubleshooting Steps Attempted (All Failed)

- ✓ App updated to latest version

- ✓ Cleared cache and app data

- ✓ Complete uninstall/reinstall

- ✓ Changed DNS (Quad9 → Cloudflare)

- ✓ Enabled microG “Google device registration”

- ✓ Verified system date/time accuracy

- ✓ Granted all app permissions

- ✓ Battery optimization set to “Unrestricted”

## Hypothesis

Bug specific to the cryptographic module of Snapdragon 7s Gen 4 under /e/OS, or microG incompatibility with this hardware architecture.

## Request

- Investigation into compatibility with Fairphone 6+ /e/OS

- Workaround solution if available

- Notification when a fix is deployed

I managed to connect to all Proton apps by means of a QR code:

Sign in on another device How to connect with a QR code

1. Open any Proton app from the device you want to connect to.

2 On the login screen, select Password • Forgot or Login issues? (on mobile apps, select Help

3 Select Sign in with a QR code.

A QR • Code will appear.

4 On this device, tap Scan QR code and • Scan the code.