What is the error? It was normal some time ago... https://gyazo.com/e092d24130aae29c9a696eaab0dcffed

Good day, Yury.

You'll want to perform these steps to see if this is just a browser error.  First, use an incognito window and split the transactions from there. Also, let's clear the cache since it can cause issues in QuickBooks Online.

Lastly, make sure that the browser is updated. You can use a different one if there's available.

Post again here if you have other questions. Stay safe!

I have used incognito and other browser but the error is still happen.

I can't make a split transactions from the rule in bank section.

Hi there, @Yury.

I appreciate you for getting back to us here in the Community. Let me provide some information about what to do next to split transactions successfully in the Banking section.

Since the problem persists after performing the necessary troubleshooting, I suggest you proceed with contacting our QuickBooks Support Team. You can use the Start a chat feature from the Help menu for them to securely access your account and assist you further with the banking issue.

Here's how:

1. Click Help in the upper-right corner.
2. Select Contact Us.
3. Enter your specific concern in the What can we help you with? box. 
4. Click Let's talk. 
5. Select Start a chat. 
6. Enter your contact information. 
7. Hit Submit.

For additional reference, you can use the following article to re-upload or manually upload bank transactions in QuickBooks: Manually upload transactions into QuickBooks Online.

Leave a comment below if you have other concerns. The Community and I will be around to help you.