Apple Intelligence is now available on iPhone, iPad, and Mac!

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Time machine, Next backup: When disk is connected

Hi! I have confronted this problem for a couple of weeks now so I've decided to ask somebody else to help me in this situation.

I think is pretty clear what is happening: Time Machine won't work. It clearly says that the next backup will occur when the disk is connected. Latest backup has been done on May 23 2019 and i still have 700+GB of storage on the personal disk. The backup has 109GB!


I am on a macOS Mojave, 10.14.5, if that helps!


Thank you!

MacBook Air 13″, macOS 10.14

Posted on Jul 28, 2020 1:07 AM

Question marked as Top-ranking reply

Posted on Jul 30, 2020 9:02 AM

That's ok.


First, de-select "Back Up Automatically" to make sure no backups are in progress. Then, go ahead and click Remove Disk and confirm the dialog box that appears next: Stop Using This Disk.


That action does not affect its existing backups.


Then, physically disconnect the drive from that Mac and connect it again. Wait for its icon to appear on the Desktop, assuming you selected External Disks in the Finder's Preferences.


Then, Select Disk... again in Time Machine's Preferences. Re-select the same one under Available Disks, then Use Disk.


"Waiting to complete first backup" will appear, which means it won't do anything until the next scheduled backup. Despite the implication of that message, it does not mean it needs to create a completely new backup, as if it's creating a brand new one. Your existing backups will still be available.


If you don't want to wait that long, select Back Up Now.


A Notification may appear if your source volume is encrypted and the backup volume is not. That's normal, although you really ought to consider using encryption. Selecting "Encrypt backups" will require erasing the existing ones first so that's a concern to be addressed later.


Re-select Back Up Automatically. The "Preparing Backup..." status message will remain for a long time. Eventually, "Backing up xxx of yyy" will appear, but those values will not be accurate, nor will the "Estimated time remaining" in Time Machine's Preferences. Just ignore it. It may take a few hours even if your Mac is not allowed to sleep. Time Machine will also pause or become slow if you use your Mac for tasks it considers a higher priority.


If the above does not occur for whatever reason, consider the possibility the backup disk has failed, perhaps catastrophically, and it might not even appear in the Finder. You can determine that by using Disk Utility.

3 replies
Question marked as Top-ranking reply

Jul 30, 2020 9:02 AM in response to Community User

That's ok.


First, de-select "Back Up Automatically" to make sure no backups are in progress. Then, go ahead and click Remove Disk and confirm the dialog box that appears next: Stop Using This Disk.


That action does not affect its existing backups.


Then, physically disconnect the drive from that Mac and connect it again. Wait for its icon to appear on the Desktop, assuming you selected External Disks in the Finder's Preferences.


Then, Select Disk... again in Time Machine's Preferences. Re-select the same one under Available Disks, then Use Disk.


"Waiting to complete first backup" will appear, which means it won't do anything until the next scheduled backup. Despite the implication of that message, it does not mean it needs to create a completely new backup, as if it's creating a brand new one. Your existing backups will still be available.


If you don't want to wait that long, select Back Up Now.


A Notification may appear if your source volume is encrypted and the backup volume is not. That's normal, although you really ought to consider using encryption. Selecting "Encrypt backups" will require erasing the existing ones first so that's a concern to be addressed later.


Re-select Back Up Automatically. The "Preparing Backup..." status message will remain for a long time. Eventually, "Backing up xxx of yyy" will appear, but those values will not be accurate, nor will the "Estimated time remaining" in Time Machine's Preferences. Just ignore it. It may take a few hours even if your Mac is not allowed to sleep. Time Machine will also pause or become slow if you use your Mac for tasks it considers a higher priority.


If the above does not occur for whatever reason, consider the possibility the backup disk has failed, perhaps catastrophically, and it might not even appear in the Finder. You can determine that by using Disk Utility.

Time machine, Next backup: When disk is connected

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.