error massage

Have you rund the Verify/Rebuild data utility? Have you run the Tool Hub? How big is the file size?

Hi there, @KH Omran.

In addition to @Fiat Lux - ASIA's answer, you can also update your QuickBooks Desktop. Then, re-sort the list your Chart of Accounts if you've still encounter that notification. This will make your list go back to its default order. I'd be glad to show you the steps. 

1. Go to the Lists menu, select either Chart of Accounts.
2. Select the Account drop-down button.
3. Click Re-sort List.
4. Select OK.

Here's a screenshot for your additional reference:

If you can see the same error upon assigning an account, I'd suggest repairing the QuickBooks Data file. For more information, please refer to this article: Fix data damage on your QuickBooks Desktop company file.

You are always welcome to get back to this thread and tag my name if you need further assistance or questions. I'd be happy to guide you through it. Take care.