Hi there! I see you're encountering error 40018 when trying to open your booking on the Avis app. Let's work on identifying what's causing that and getting you back on track.

To help me understand better, could you tell me:
- Are you signed into your Avis account on the app?
- Does this happen with all bookings or just one particular reservation?
- When exactly does the error appear — right after logging in, when selecting the booking, or another step?
- Have you tried any fixes so far, like restarting the app or your phone?

In the meantime, here are some simple steps that often help resolve booking access errors:

1. Update the Avis app: Ensure you are running the latest version from the Google Play Store, as outdated apps can have bugs.
2. Log out and back in: Sometimes, session issues cause errors; logging out and signing back in refreshes your credentials.
3. Clear app cache and data: On Android 10, go to Settings > Apps > Avis > Storage, then clear cache first, then if needed clear data (note: clearing data may require you to log in afresh).
4. Check your internet connection: Switch between Wi-Fi and mobile data to rule out connectivity glitches.
5. Verify booking details: Confirm your booking exists and is active on the Avis website via a desktop or browser.

If those don't work, it might be an issue with your account or an internal server problem. In that case, I can help you contact Avis support directly or guide you through advanced troubleshooting.

Let me know what you’ve tried and any other details you noticed! We'll get this sorted out together.