macOS Catalina Known Issues

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Emerging issue: macOS may fail to create disk images on some SMB volumes

We have received several reports that macOS is unable to create disk images on SMB volumes hosted by various NAS devices (e.g. FreeNAS device, Western Digital MyCloud Home and QNAP). If you attempt to create the disk image in Disk Utility (for example), Disk Utility reports an "RPC Error".

Workaround: Several users are reporting that connecting to the network volume via AFP rather than SMB resolved the problem:

  1. Eject the NAS volume if it's currently mounted
  2. Choose "Connect to Server" from the Finder's Go menu
  3. Type in "afp://{server address}" to connect to the NAS volume via AFP
  4. Choose "New disk image..." from CCC's Destination selector and specify a new disk image on the AFP-mounted NAS volume

Startup Disk Preference Pane doesn't show OS versions for external volumes

The System Preferences application lacks full disk access by default, so it cannot read the System Version file on external volumes for the purpose of presenting the system version string underneath the volume icons. Ironically, System Preferences has the privilege to change the startup disk, but it can't make a read-only access to the system version file on external volumes.

Solution: Open System Preferences > Security & Privacy > Privacy, click the padlock icon and authenticate when prompted, then add the System Preferences application to the Full Disk Access category.

We have reported this issue to Apple (FB6723060) and we are currently awaiting a response.

Spotlight's "mds" helper processes aggressively dissent volume unmount requests

During our Catalina testing we repeatedly had trouble unmounting volumes in Disk Utility, particularly when erasing a backup volume. Upon closer inspection we found that an mds process is nearly always the dissenting process. We've seen this occasionally in the past, and for a long time CCC's option to unmount the destination volume at the end of a backup task has worked around the occasional Spotlight dissent with a followup forced-unmount. In Catalina, however, the problem seems to be far worse, affecting nearly every casual unmount attempt (except in the Finder, oddly).

Workaround for general unmount annoyances: You can disable Spotlight on your CCC backup volume to avoid its interference (and for better performance in general). To disable Spotlight, open the Spotlight preference pane in the System Preferences application, click on the Privacy tab, then drag the backup volume into the Privacy table. This only affects the destination volume, and it's reversible, you can remove it from that list should you decide that you want to re-enable indexing.

Workaround when attempting to erase a volume: If you're trying to erase a volume in Disk Utility and Disk Utility is reporting that it cannot unmount the volume to erase it — brace yourself for this one — unmount the volume before erasing it. That's right, Disk Utility can't walk and chew gum at the same time. If you unmount the volume before erasing it, though, the unmount request typically succeeds and you're then able to erase the volume.

We have reported this issue to Apple (FB6905679) and we are currently awaiting a response.

Resolved Issues

On login, macOS fails to unlock and mount the Data volume of an encrypted APFS volume group

If you have an installation of macOS Catalina on a separate volume (e.g. a backup disk) and FileVault is enabled on that volume, the prompt to unlock the volume only unlocks the System volume. If the Data volume is not unlocked and mounted, the volume does not work correctly and the bulk of your data will appear to be missing.

Workaround: You must manually mount the Data volume in CCC (or Disk Utility) to get access to your data on the backup: Right-click the Data volume in CCC's sidebar and choose Mount.

We have reported this issue to Apple (FB6786776) and we are currently awaiting a response.

Update: This issue appears to be resolved in Catalina Beta 7.

The APFS filesystem causes a kernel panic when remounting the System volume in an encrypted APFS volume group

If you unmount and then remount the System volume (or sometimes when you then unmount the System volume again) in an encrypted APFS volume group, the system will kernel panic. CCC will only need to mount or unmount the System volume of the backup disk during a backup task if changes have been made to the source System volume (e.g. after applying an software update). If a kernel panic occurs, simply re-run the backup task after the system reboots to complete the backup.

Partial mitigation: Disabling Spotlight on the destination appears to reduce the incidents of kernel panics. To disable Spotlight, open the Spotlight preference pane in the System Preferences application, click on the Privacy tab, then drag the backup volume into the Privacy table. This only affects the destination volume, and it's reversible, you can remove it from that list should you decide that you want to re-enable indexing.

Update: This issue appears to be resolved in Catalina Beta 9.

System Preferences cannot enable FileVault on external volumes

This is an emerging issue as of Catalina Beta 6. When attempting to enable FileVault on an external volume (whether it is a backup or an installation placed there by the Installer), the FileVault preference pane claims:

FileVault Failed [sic]
This operation is restricted by your settings in System Preferences > Security & Privacy > Privacy > Files and Folders.

The meaning of this dialog is ambiguous, and you can't actually make configuration changes in the "Files and Folders" category. In fact, the problem is not that you have misconfigured something in "Files and Folders", rather some component of the Security Preference Pane, or a service that it relies upon to enable FileVault lacks access to external volumes (i.e. "Full Disk Access"). The identity of that service is not made clear by this dialog.

We have reported this issue to Apple (FB7083306) and we are currently awaiting a response.

Update: This issue appears to be resolved in Catalina Beta 7.