Could you please let me know the name of your financial institution and any specific error message you're seeing? Any details you can share will help me find the best solution for you.
To start, please note that under Open Banking regulations, QuickBooks can only connect with supported financial institutions. You can visit this article to check if your bank is supported.
If it is listed as supported, please log directly into your bank's website to check for any alerts, notifications, or scheduled maintenance, as these can easily disrupt the connection to QuickBooks.
If none, let's try connecting your bank using an incognito window. Issues like this can arise due to accumulated cache in your regular browser. Utilizing a private window can bypass the stored cache and help isolate the problem.
If it works in the private window, you can return to your regular browser and clear its cache, but not the cookies, to give it a fresh start. Alternatively, you can try using a different browser.