I can share the reason behind the error and help you get rid of it, cjwm.

We can double-check within the app if there's ongoing maintenance. If none, we can open your account in an incognito mode to see if this has something to do with your browser. Whenever you visit a website, it saves some information from the web page in its cache and cookies.

Here's how to access incognito mode in some of the most commonly used web browsers:

• Google Chrome: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift + P
• Microsoft Edge: Ctrl + Shift + P
• Safari: Command + Option + P

If you're able to connect an app by browsing privately, it's safe to say that it's being caused by the browser. It can be fixed by clearing your cache and cookies.

In the event it continues occurring while using incognito, you'll initially have to try switching to another browsing application.

Here's a list of supported browsers:

• Google Chrome
• Mozilla Firefox
• Safari 11 or newer

Feel free to comment below if you have other concerns besides connecting an app on QuickBooks Online. We are eager to help you. Stay safe!