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Time Machine Erroneously Says Next backup "When disk is connected"

Since upgrading a MacBook Pro and an iMac to High Sierra (10.13.3), I have noticed the following anomaly with Time Machine.


1. If I access TM from the Menu Bar icon ("Open Time Machine Preferences"), TM reports "Next backup: When disk is connected", even though a disk is already connected (and accessible through Finder). [If I then un-check the "Back Up Automatically" box, and then immediately re-check it, the next backup time is correctly displayed; however if the window is closed, and then re-opened from the Menu Bar, the original erroneous message is again displayed.]


2. But if TM is accessed through the System Preferences panel, it correctly reports the time of the next backup.


TM is otherwise functioning correctly; but you'd expect the TM preference screen to show the same result, whether it was accessed via methods #1 and #2 above. But it doesn't.


My MacBook Pro is using a 1 TB Seagate Backup Plus external drive; the iMac is using a 2 TB WD Elements external drive. Both external drives are partitioned to allocate 75% of their space to Time Machine, and 25% of their space for other purposes.


This issue did not appear prior to my upgrading from Sierra to High Sierra. Given that it appears on two different Mac models, and two different manufacturers' external drives, my sense is that this is a High Sierra issue.

Posted on Mar 17, 2018 10:16 AM

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Posted on Mar 17, 2018 10:55 AM

A Troubleshooting Procedure that may Fix Problems with macOS El Capitan or Later

You should try each, one at a time, then test to see if the problem is fixed before going on to the next.


Be sure to backup your files before proceeding if possible.


  1. Shutdown the computer, wait 30 seconds, restart the computer.
  2. Disconnect all third-party peripherals.
  3. Resetting your Mac’s PRAM and NVRAM
  4. Reset the System Management Controller (SMC)
  5. Reset your Startup Disk and Sound preferences.
  6. Start the computer in Safe Mode. Test in safe mode to see if the problem persists, then restart normally.
  7. Use Apple Hardware Test to see if there is any hardware malfunction.
  8. Repair the disk by booting from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volume entry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and return to the Utility Menu. Restart the computer from the Apple Menu.
  9. Repair permissions on the Home folder: Resolve issues caused by changing the permissions of items in your home folder.
  10. Create a New User Account Open Users & Groups preferences. Click on the lock icon and enter your Admin password when prompted. On the left under Current User click on the Add [+] button under Login Options. Setup a new Admin user account. Upon completion log out of your current account then log into the new account. If your problems cease, then consider switching to the new account and transferring your files to it - Transferring files from one User Account to another.
  11. Download and install the OS X El Capitan 10.11.6 Combo Update or 10.12.6 Combo Update or Download macOS High Sierra 10.13.3 Combo Update as needed.
  12. Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
  13. Erase and Install OS X Restart the computer. Immediately after the chime hold down the Command and R keys until the Apple logo appears. When the Utility Menu appears:
  1. Select Disk Utility from the Utility Menu and click on Continue button.
  2. When Disk Utility loads select the drive (out-dented entry) from the Device list.
  3. Click on the Erase icon in Disk Utility's toolbar. A panel will drop down.
  4. Set the Format type to APFS (for SSDs only) or Mac OS Extended (Journaled.)
  5. Click on the Apply button, then wait for the Done button to activate and click on it.
  6. Quit Disk Utility and return to the Utility Menu.
  7. Select Reinstall OS X and click on the Continue button.

If none of the above helps then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.


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4 replies
Question marked as Best reply

Mar 17, 2018 10:55 AM in response to MichiganBanjoMan

A Troubleshooting Procedure that may Fix Problems with macOS El Capitan or Later

You should try each, one at a time, then test to see if the problem is fixed before going on to the next.


Be sure to backup your files before proceeding if possible.


  1. Shutdown the computer, wait 30 seconds, restart the computer.
  2. Disconnect all third-party peripherals.
  3. Resetting your Mac’s PRAM and NVRAM
  4. Reset the System Management Controller (SMC)
  5. Reset your Startup Disk and Sound preferences.
  6. Start the computer in Safe Mode. Test in safe mode to see if the problem persists, then restart normally.
  7. Use Apple Hardware Test to see if there is any hardware malfunction.
  8. Repair the disk by booting from the Recovery HD. Immediately after the chime hold down the Command and R keys until the Utility Menu appears. Choose Disk Utility and click on the Continue button. Select the indented (usually, Macintosh HD) volume entry from the side list. Click on the First Aid button in the toolbar. Wait for the Done button to appear. Quit Disk Utility and return to the Utility Menu. Restart the computer from the Apple Menu.
  9. Repair permissions on the Home folder: Resolve issues caused by changing the permissions of items in your home folder.
  10. Create a New User Account Open Users & Groups preferences. Click on the lock icon and enter your Admin password when prompted. On the left under Current User click on the Add [+] button under Login Options. Setup a new Admin user account. Upon completion log out of your current account then log into the new account. If your problems cease, then consider switching to the new account and transferring your files to it - Transferring files from one User Account to another.
  11. Download and install the OS X El Capitan 10.11.6 Combo Update or 10.12.6 Combo Update or Download macOS High Sierra 10.13.3 Combo Update as needed.
  12. Reinstall OS X by booting from the Recovery HD using the Command and R keys. When the Utility Menu appears select Reinstall OS X then click on the Continue button.
  13. Erase and Install OS X Restart the computer. Immediately after the chime hold down the Command and R keys until the Apple logo appears. When the Utility Menu appears:
  1. Select Disk Utility from the Utility Menu and click on Continue button.
  2. When Disk Utility loads select the drive (out-dented entry) from the Device list.
  3. Click on the Erase icon in Disk Utility's toolbar. A panel will drop down.
  4. Set the Format type to APFS (for SSDs only) or Mac OS Extended (Journaled.)
  5. Click on the Apply button, then wait for the Done button to activate and click on it.
  6. Quit Disk Utility and return to the Utility Menu.
  7. Select Reinstall OS X and click on the Continue button.

If none of the above helps then make an appointment at the Apple Genius Bar for service. If you need to find an Apple Store - Find a Store - Apple.


Time Machine Erroneously Says Next backup "When disk is connected"

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