There are a number of different reasons why a Destination Unavailable message appears in CrashPlan:
This article explains causes for each of these circumstances.
“Destination unavailable. Backup location is not accessible” means that the location of the archive on the destination computer is currently unavailable. This could be because the drive is not currently mounted or because permissions do not allow access. It could also signify a network issue.
This issue is typically caused by a drive that didn't cleanly unmount (e.g., due to a power outage, disconnected without ejecting, etc.). When this happens, the drive can leave behind a "ghost" folder in
/Volumes, even though the drive is no longer mounted. When the drive re-mounts, your Mac sees that the folder name for the drive is taken, so it appends a “1” to the drive name. However, CrashPlan is looking for the folder with the original name, which is no longer valid.
To determine if you have a duplicate drive:
Do you see the external drive name? Do you see one ending with a “1”? If so, this duplicate drive is causing the issue.
For more information, see our troubleshooting guide, External Drive Stops Backing Up, or the Apple Support article Duplicate mount point in /Volumes after unexpected restart.
If you receive the message “Destination unavailable. Backup location is not accessible”, and an accidentally unmounted external drive does not appear to be the source of the issue, you may have a network issue.
Certain applications are known to conflict with the CrashPlan app and may result in a Destination Unavailable message. Antivirus and security applications are the most common source of conflict; however, additional programs have been known to cause conflicts as well. Identify whether or not an application is conflicting with CrashPlan.
This message has two possible causes:
Both settings can be adjusted in the CrashPlan app from Settings > General. Increase the time period during which CrashPlan is allowed to run or increase CrashPlan's allowed CPU usage to reestablish back up to the destination.
The destination computer is currently performing Archive Maintenance / the Compact routine. The "Destination Unavailable" message will disappear once the maintenance process is complete.
Your friend has restricted the amount of space your backup can take up on his or her computer and you've reached your limit. Files are still available for restore, but no additional files can be backed up to this destination.
To continue backing up to your friend's destination, either adjust your file selection to make the backup smaller, modify your frequency and version settings, or ask your friend to increase the allotted space for your backup.