Let's isolate this issue by running some troubleshooting steps, Farzana.
To start with, let's open your QuickBooks account in a private window. This is the best place to identify any browser-related concerns.
I've added these keyboard shortcuts to open one:
If you're able to log in without error, we can go back to your main browser and clear its cache. A piled cache can also be the reason for some unexpected issues on the opened pages. We can also use a different supported browser like Google Chrome, Mozilla Firefox, Microsoft Edge, or Safari.
Let me know if you have other concerns.