Our company BMO Mastercard was previously connected with our QBO but starting about a month ago, it got disconnected. We're trying to reconnect it numerous but to unable.

Try opening your QBO account on any private/incognito browser.

Hello junlomb. I'd like to help make sure you're on the right track with your banking. In case you're getting an error message, I recommend checking out the articles below that help you fix the errors in the program:

• Fix banking error 324
• Fix banking error 155
• Fix banking error 103
• Fix banking error 101
• Fix banking error 192
• Fix banking error 106
• Fix banking error 187
• Fix banking error 109
• Fix banking error 323

I encourage you to identify the error number on your end and click on the article which matches that error number above. I also suggest clearing cache and cookies on your browser. This is a great way to clean your browser allowing it to work more efficiently. Here's a helpful article that shows you how to clear cache and cookies. 

In case this issue persists, I encourage you to contact our support team so they can assist you further with this. Here are our contact details: 

• Schedule a Callback or start a Chat: click (?) in the upper right in QuickBooks Online > enter "Contact support" > choose Contact Us > provide a brief summary > select Let's Talk > choose Get a callback or Start a Chat.
• Social Media: Facebook, Twitter, and Instagram.
• Support hours are from Monday to Friday between 9 a.m. and 8 p.m. ET.

Feel free to keep me posted on how you make out. I'll be one message away.