I Having banking connecting error (106). What should I do in this case?

Let's re-establish your bank connection, @qotayba.

Bank error 106 means QuickBooks is unable to locate your account on your bank or financial institution's website. This typically occurs when the account is closed.

If your account is still active, we can refresh the connection by disconnecting and reconnecting it. Before we start, ensure the account isn’t linked to your chart of accounts.

Here’s how to disconnect your bank account:

1. Go to Bank Transactions and select the tile for your bank account.
2. Click the pencil icon and choose Edit account details.
3. Check the box for Disconnect this account on save.
4. Click Save.

Once the account is disconnected, follow the steps in this article to reconnect your bank: Connect bank and credit card accounts to QuickBooks Online.

If you have any further questions or need assistance, please reply to this thread.

@qotayba--hamada 

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