Hi there, @soshagayle,
Let’s work together to get past the error so you can back up your company file in QuickBooks for Mac.
Mac has a built-in disk utility that QuickBooks uses to create a DMG (image) file when backing up company files. The error message you’re getting usually appears when something prevents this process from happening.
We’ll need to verify the data to help detect the cause of the error, then run rebuild to resolve it.
Here’s the article that details the steps to run the verify and rebuild utilities: Resolve data damage on your company file
Once the rebuild completes, please verify the data again to ensure there aren’t any other issues in the company file.
If you’re still unable to back up the file, I recommend getting in contact with our QuickBooks for Mac Technical Support Team for further assistance. Here’s how:
1. Click this link: https://help.quickbooks.intuit.com/en_US/contact
2. Select QuickBooks Mac Desktop.
3. Select a topic and a sub-topic in step 1.
4. Click Get Phone Number in step 2.
Stay in touch with me if there’s anything else you need while working in QuickBooks for Mac. I’m here to help however I can.