Hi there, rozita-arscm.
This error occurs if there's an issue with the browser. You'll want to use an incognito window and do your tasks from there. Here are the keyboard shortcuts:
Also, let's clear the cache since it causes errors in QuickBooks Online. Lastly, make sure that the browser you're using is updated or use a different one.
Visit our QuickBooks Help page if you want tips and tricks in managing your business.
Keep on posting here if you have more questions. Stay safe!