I'm having issues with a simple part of script, where I wanna get the property dock preferences of System Events. I have the following:

tell application "System Events"
    tell appearance preferences
        set ap_prefs to (get the properties)
        set ap_prefs to the properties
    end tell
    set a_pref to the properties of appearance preferences

    tell dock preferences
        set d_prefs to (get the properties)
    end tell
    set d_pref to the properties of dock preferences
end tell

In the code above I access appearance preferences in all the ways shown above, but not dock preferences. It give an error error "System Events got an error: AppleEvent handler failed." number -10000.

So what is going on, and why is only giving error with dock? Here @dj_bazzie_wazzie says:

Error -10000…most of the time it is not a target error but an incomplete command or wrong usage of brackets.

But I can't figure out what is the proper way. I've tried all I can think of, also why doesn't it throw the exception for appearance preferences?


I've also opened this question on Stack Overflow, I'll close one when I get a answer.

  • Cross-posting is frowned upon. Pick one & delete the other.
    – Tetsujin
    Aug 16, 2015 at 15:57
  • I've seen that error when a variable expecting a POSIX file is given a string instead. Not quite sure on 'properties', though, which iirc ought to be a list... but it might be a start-point
    – Tetsujin
    Aug 16, 2015 at 16:03

2 Answers 2


This works for me in the latest version of macOS Sierra...

tell application "System Events"
    set dockPrefs to dock preferences
    set appearancePrefs to appearance preferences
end tell

this is not really an answer but a detailed "comparison".
When I had your code run on my Mac (El Capitan), including your malfunctioning "set d_prefs to the properties" line, I didn't get an error at all.
Results window in ScriptEditor read:

{minimize effect:scale, magnification size:0.178571432829, ¬
dock size:0.116071425378, autohide:true, animate:false, ¬
magnification:false, screen edge:left, class:dock preferences object}

I wonder if you tried to get these values displayed/changed and called them by index?
I just read that: "You can retrieve items from a record [= list of properties] by name, but not by index."
Maybe that's where the error came from?

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