Why is QuickBooks rejecting my login credentials?

https://quickbookhelpdesk.com/blog/why-is-quickbooks-not-letting-me-sign-in/

If QuickBooks is not letting you sign in, the problem is usually related to incorrect login information, internet connectivity, browser settings, outdated software, damaged application files, or temporary account verification rather than your company data. Fortunately, most sign-in problems can be resolved by verifying your credentials, updating QuickBooks, clearing browser cache, checking your internet connection, and restarting your device.