Why can't the "/" symbol be used in the Business Name field anymore? Some businesses need to use t/a (trading as), for example, ABC Pty Ltd t/a XYZ. Please help

The forward slash (/) is an invalid character in QuickBooks Online. Using it in your company name can lead to server errors or other application problems. To keep the account running smoothly, you'll need to use an alternative format based on the list of accepted characters.

Even though your client strongly prefers using "t/a" for "trading as," keeping the slash will likely continue to cause errors within their QuickBooks. You might suggest an alternative format that complies with the system requirements.  

If you have any other QuickBooks-related questions, you can always get back to this thread.