MacOS Catalina, Disk Utility: "Unable to perform deferred repairs"
Run Disk Utility in Recovery Mode:

Boot into Recovery mode by holding down ⌘R while powering up
Select Disk Utility
Select the &quot;Container&quot; for Macintosh HD - Data (do not select Macintosh HD - Data itself)
Click &quot;First Aid&quot; and &quot;Run&quot;
If that does not seem to fix the problem, select the Drive that contains the &quot;Container&quot; and run &quot;First Aid&quot; on it.

The above is from memory. You may need to mount or unlock the drive at some point in the above process.