I can't add my vehicle in the app, an error keeps popping up. Message: "Unknown exception: Could not parse. Locale from string; str = pl_GB"

I can share some insights on how to get around this issue, @omieczynskipatry.

You'll want to uninstall and reinstall the app. This will remove all the data save in your QuickBooks Online (QBO) Mobile App and start with a clean slate.

If the issue persists, I recommend contacting our Support team. They have the tools to securely check your account and investigate why you're unable to add a vehicle to your app.

In the meantime, you'll want to log in to your account in a regular web browser and add a vehicle from there. Let me guide you how.

1. Go to the Mileage or Trips menu.
2. Select the Vehicle icon.
3. Click Add vehicle.
4. Enter the needed info
5. Select Save once done.

You can also see this article for more details: Set up mileage tracking and vehicles in QuickBooks Online and QuickBooks Self-Employed.

Let me also add this link that lets you automatically track your mileage in QBO: Automatically track mileage in QuickBooks Online.

Keep me posted if you have other queries managing your mileage. I'll be around to help you out. keep safe!