Upgraded Mac to 10.13.6 and QB2014 doesn't run so I cannot close old file

You've reached the right support, ablech.

I want to make sure your concern with opening QuickBooks Desktop gets sorted out.

To narrow down this issue, we'll need to ensure your old company file for QuickBooks Desktop for Mac is closed. I'd be delighted to show you how by following the steps below:

1. From the Apple menu, click Force Quit or press Command-Option-Esc.
2. Choose the QuickBooks app in the Force Quit window.
3. Click the Force Quit button. 

Once done, we can now delete the lock file of your QuickBooks Desktop for Mac. 

Here's how:

1. Make sure you are in the Finder (the menu at the top will say Finder right after the Apple sign).
2. Choose File.
3. Click New Finder Window. 
4. Click on the word Documents.
5. The Finder window will now be titled Documents at the top center.
6. Select your QuickBooks Company file, it ends with .qb2014.
7. From the Finder menu, choose File.
8. Select New Folder with (name of your company file).
9. Rename the folder and double-click it, after to open it up in a finder window.
10. Select the company file to launch QuickBooks. 

If you continue experiencing the same error, I suggest contacting our Technical Support Agents so that they be able to investigate this further.

Here's how you can reach out to them:

1. Go to: https://help.quickbooks.intuit.com/en_US/contact.
2. If asked, choose your QuickBooks Product.
3. Select your QuickBooks version.
4. On the Contact Us page, click a topic.
5. Click on the Get Phone Number button to see the support number.

Keep me posted if there's anything else you need while working with QuickBooks. We'd be happy to help.