Hi there, @felsym.
Let's check if you're able to update your bank using the private browser. See it below:
If the private browser works, you can go back to your original browser and clear the cache. If using the private browser doesn't work at all, you can use another compatible browsers in QBO.
You can share further information when you experienced this error again. I'll assist you further.
Reply to this thread anytime if you have other questions.