You may see this error message when the add-on can't connect with our server while trying to pull up the Article summary from our webpage. You can try these troubleshooting steps to address the issue:
* make sure you have a stable internet connection
* re-log to your AMBOSS account within Anki, you can click on AMBOSS > Log out... You can log in again via the same menu
* check if you can use our webpage without any issues
If the above solution did not help and you can't access our webpage, please reach out to us through our contact form.