QB 2020, Merge Classes & Warning Message

I appreciate you for upgrading your QuickBooks Desktop for Mac to the latest version. Let's perform some steps to merge your classes, BDGmic.

I've checked here on our records and there's no reported case about this error message when merging classes. You can merge two classes through editing the second class and make the name identical to the first class. The system will detect an existing class with the same name you're trying enter then will ask you two merge these classes instead.

However, we can't combine more than two items at a time. Also, the option to combine items if both have sub-items is unavailable. We'll need to first remove the sub-items from the items you want to remove. Once done, identify which Class name you want to keep and which one you want to combine. Just follow the steps below to merge them: 

1. Go to Lists on the top menu. 
2. Choose the Class List.
3. Select a class, then change the Class name with the same class that you want to merge.
4. There will be a prompt message, just tap Yes.

To check if the two classes are merged, just right-click the class and choose QuickReport. Once you merge two items, we can't reverse it and all transactions (even in closed periods) will be under one item. It may also affect previous financial reports and the data associated with the merged item is removed from your records along with the item itself.

To learn more about how to add, edit, and delete items in QuickBooks Desktop for Mac, see Add, edit, and delete items article for more details.

If the same thing happens, there may be a damaged data on the company file you've been working with. We can run the Rebuild Data tool is built-in to fix any company file data issues.  Just follow the steps and detail in his article: Fix data damage on your QuickBooks Desktop company file.

I'd like to know how you get on after trying the steps, as I want to ensure this is resolved for you. Feel free to reply to this post and I'll get back to you. Take care always.