Here are some questions and problems that people often encounter when using Jettison.
Before consulting this list or contacting us, please make sure you
are using the latest release of Jettison, version 1.7.2.
If you have a problem that is not addressed here or feel a question should
be here but isn't, please send mail to firstname.lastname@example.org
I've installed Jettison, but I'm still getting "Disk
ejected improperly" errors. Why isn't Jettison working?
Jettison is almost certainly ejecting your drives as it's supposed to, but there
are some features in macOS that can still cause the error messages to show
The short answer: Turn off problematic sleep behaviors using this applet:
(it also provides a button to turn them back on if you change your mind). Note: Among other things, this disables the TCP Keep Alive mechanism when the sytem is sleeping. This will result in Find My Mac not updating its location when the system is asleep.
The long answer(s):
The most common source of problems is the Power Nap feature in macOS (http://support.apple.com/kb/ht5394).
What happens is that Jettison ejects your external drive when you put your
computer to sleep, but your Mac wakes up later via Power
Nap and tries to do a Time Machine backup. Time Machine attempts to write data
to the drive even though it is not there, which causes the disk journaling
system (part of macOS that ensures data on your disk doesn't get corrupted)
to save the data so it can write it to the disk later. Then, when the computer
wakes up and the disk remounts, macOS sees an inconsistency between the data
in the disk journal and the drive, so it puts up the warning message.
If you have a Mac that supports Power Nap, you can see if this is the problem
by opening the Energy Saver preferences in System Preferences and turning off
Power Nap. Note that if you're on a MacBook Air or MacBook Pro, you must turn
off Power Nap in the "Power Adapter" tab of your Energy Saver preferences.
MacBook models released after mid-2012 (and MacBook Airs after mid-2010) will enter
"safe sleep" mode after being asleep for a specific amount of time. The transition from
normal sleep to safe sleep can sometimes result in the "Disk ejected improperly" error
You can disable safe sleep using the following commands in Terminal:
sudo pmset -a hibernatemode 0
sudo pmset -a autopoweroff 0
sudo pmset -a standby 0
For more information on safe sleep, hibernation, standby and autopoweroff
modes, see this article: http://apple.stackexchange.com/questions/113954/difference-between-autopoweroff-and-standby-in-pmset.
Apple also has its own Knowledge Base articles discussing
and autopoweroff (http://support.apple.com/kb/HT1757).
In the Energy Saver pane in System Preferences, turn off "Wake for
network access." That can sometimes cause your Mac to partially wake from sleep,
resulting in "Disk ejected improperly" error messages even though the disk
was ejected correctly.
Note that this may still not be enough, as the Find My Mac feature may also periodically wake up the machine. To turn all "dark wake" features off, use this command in Terminal:
pmset -a tcpkeepalive 0
or download and run the applet given in the "short answer," above.
I bought Jettison in the Mac App Store, but it is now telling me my trial is over.
Apple periodically changes the signing certificate in its Mac App Store receipts. If you bought Jettison
through the Mac App Store and then upgraded to a newer version from our web site using the instructions below,
you may suddenly be getting messages that your trial period is over. This is because the original receipt that Jettison copied from your Mac App Store version of Jettison is no longer valid.
You cannot get a license code from us to activate your copy of Jettison. You need to follow these instructions:
- Put all copies of Jettison in the Trash and empty the Trash.
- Open the App Store application and click on the Purchases tab.
- Install the copy of Jettison you purchased (if the button says 'update' go back to step #1).
- Download the latest version of Jettison here: http://www.stclairsoft.com/download/Jettison-1.7.1.dmg
- Click on the .dmg file to open it, then double-click on Jettison before copying it to your Applications folder.
- After Jettison tells you that it has found your App Store license, you can quit it and copy it to your Applications folder.
Sorry for the trouble, but this is not something we anticipated when we implemented the ability to upgrade from your App Store-purchased copy to a newer version from our website.
I bought Jettison through the Mac App Store. Can
I upgrade directly from your web site?
Yes, just download the latest version of Jettison here.
Before copying the
new version to your Applications folder, however, please double-click it to
run it once directly from the disk image. Jettison will
make a copy of your App Store receipt (which is embedded in the Jettison application
that you downloaded from the Mac App Store). You can then copy Jettison to
your applications folder, deleting the version that you got from the Mac App
If you've already replaced your App Store copy of Jettison without running
it first, you'll need to backtrack a bit. Please do the following:
- Delete all copies of Jettison from your Mac.
- Open the App Store application and click on the Purchases tab.
- Find Jettison in your list of purchases and re-download it.
- Visit our website again and download Jettison from http://www.stclairsoft.com/Jettison/
- Click on the .dmg file to open it, then double-click on Jettison there.
- Copy Jettison from that window to your Applications folder.
Why can't Jettison eject one of my external
This happens when an application is accessing a file on your external drive.
Because the application will expect the file to still be there when your Mac
wakes back up, macOS won't let Jettison eject the drive. To fix this, you
need to determine which application is using the drive and either close the
file(s) that are on the drive or quit the application completely. Jettison
attempts to diagnose the problem and will let you know which files are open
if it can determine that.
How can I stop Jettison from remounting drives when my Mac wakes up?
- Select "Preferences" from Jettison's menu in the menubar.
- Click on the "Extras" tab.
- Turn off "Remount drives upon wake-up".
If you want to prevent just a single drive from remounting, you can add it to the "Don't remount these disks..." list in Jettison > Preferences > Extras.
Can I control what Jettison does with one specific disk or device?
Sure. Choose "Preferences" from Jettison's menu in the menubar,
then click on the "Extras" tab in the preferences dialog. You'll see this:
You can choose drives from the "Also unmount internal disks", "Don't unmount external disks" and "Don't remount these disks" menus to fine tune what you want Jettison to do.
Jettison ejects my drives when I put my Mac to sleep manually, but not if it sleeps due to being left idle.
In many cases, this is due to the fact that your Mac, when left idle, isn't
actually going to sleep - it's just turning the display off. This can be caused
by a number of things, most often some software or hardware that explicitly
prevents macOS from entering sleep mode. You'll have to determine which application is keeping your Mac from sleeping - the easiest thing to do is to run the Terminal application and enter this command into it:
pmset -g assertions
Look for the string "PreventUserIdleSystemSleep" in the output - the application that made the request should be listed at the beginning of the line.
Jettison will not start up. It keeps saying it needs
to install its helper application and asking me for my administrator password.
This happens when another application has installed a helper app into the folder "/Library/PrivilegedHelperTools/" and has given the folder the wrong security permissions.
The easiest way to fix this is to download an AppleScript we've created called "Fix
PrivilegedHelperTools permissions". You can get it by clicking
unzip the script application, double-click it, and type your administrator
password into the dialog box that comes up. After doing so, you should be
able to launch Jettison and install its helper application successfully.
How do I uninstall Jettison?
Just open your Applications folder and drag the Jettison application to the Trash.
If Jettison has installed its helper application, you can also remove that too, though it's not necessary to do so - the helper will never run once you remove the Jettison application from your computer. To remove the Jettison helper app, just locate and throw this file into the Trash:
or just download and run this AppleScript applet:
Note that in either case you'll need to enter your Mac's administrator password to remove the helper app.