I have been helping with a recent issue in the French banking app called Mes Comptes BNP Paribas that is made by BNP Paribas bank in France. There is no solution yet, but I will share what I have tried so far to fix the issue so that you know what will not work.

• App name: Mes Comptes BNP Paribas
• Versions 4.31.0 and 4.31.1
• App ID: net.bnpparibas.mescomptes

Accessing the app gives the following error:

ERREUR TECHNIQUE
Erreur lors du chargement de la transaction. "81"
FERMER

The apps technical support is giving another error:

Web page not available
The web page https://w-services.bnpparibas.net/mobil ... rc=webview could not be loaded because:
net::ERR_CONNECTION_ABORTED

I got the following emails from BNP banking app support when trying to figure out what was wrong:

On Fri, 26 Mar 2021, 19:34 paris_bddf_support_mobile@bnpparibas.com wrote: 81 error is due to a rooted android phone

On Mon, 29 Mar 2021, 18:48 paris_bddf_support_mobile@bnpparibas.com wrote: we used a library to protect your bank account of the fraud. This lib was a black box, i don't have all the cases that can launch a 81 error (security pb).

This was strange, because the phone is not rooted. After uninstalling and reinstalling the app, I got a different error messages claiming that the digital key was already used in another phone when it actually had been used in that very same phone only, and when I tried to re-validate the digital key by SMS, I got a new error "Une erreur inattendue est servenue" meaning that there was an unexpected error.

After taking the following steps the app started to work again and re-activate the digital key:

1. contact paris_bddf_support_mobile@bnpparibas.com and ask them to revoke your digital key
2. uninstall the app and reboot your phone
3. re-install the app and reboot your phone
4. make sure the app has at least the following permissions: Contacts, Location, Storage and Telephone
5. login to the app, go to your profile and activate digital key using SMS (follow the instructions BNP gave you)

Please note, that you will not be able to input the code that is sent by SMS manually although there is a functionality to do that in the app. The app does not accept white spaces in the code and those represent invisible character codes that the app needs to read automatically from the SMS to work properly. If nothing else works, you can also try "I want to be called" functionality which is free according to BNP support.

While following the steps, simply reboot the phone if you get following error message:

ATTENTION
Une erreur est survenue lors de cette opération. "-10"
OK

App is finally working (except the technical support page) after being broken almost 2 weeks. If you have any issues applying this fix, questions or you managed to fix your app using my instructions, please share your experiences by replying to this post. I am happy to help.

Happy hacking,

Santeri

Merci!

If you root your phone, install Magisk to ensure compatibility with some applications.
In Magisk, you have an option to verify that you pass Google's SafetyNet, which checks that the phone is clean.
The basicIntegrity level is usually easy to pass, but the ctsProfile requires that you also modify the system props, as explained here:
https://forum.xda-developers.com/t/fix-magisk-manager-20-3-ctsprofile-false-gpay-and-banking-apps.4080921/
Once you pass SafetyNet properly:
- Uninstall your banking app
- Reinstall and check that is has all its requested permissions (LineageOS or other custom distributions may limit default permissions)
- Go the shield icon in the bottom of Magisk and open the MagiskHide menu. Then select your banking app. Now, the banking app should "see" a pristine phone with a valid SafetyNet.
- Restart your phone, in case the banking app preloads some code.
- Then only, open the banking app and activate the digital key.

The above procedure was needed for me, not just a reinstall/restart, but it works!
Having a clean SafetyNet will also help for other sensitive apps.