Remote Apple Events allows you to use AppleScript routines to control another Mac; however, if you have installed the latest security updates for OS X, then you might find your scripts and any programs that use Remote Apple Events may not work, and give you an error. This may be especially true for communication between systems running OS X 10.8 and 10.9 Server, and OS X 10.10.

The communication for Remote Apple Events occurs through the “eppc” protocol, which you can use like a standard “ftp” or “http” protocol to address a target machine and send commands to it. If you use AppleScript regularly then you may be familiar with this, but a simple approach is the following:

1. Turn on Remote Apple Events in the Sharing system preferences of one Mac
2. Open the Script Editor on another Mac on the same network
3. Type the following command, replacing COMPUTER-NAME with the bonjour name or local IP address of the target Mac:

tell application "Finder" of machine "eppc://COMPUTER-NAME” to activate

This routine should require you to authenticate, and then activate the Finder on the remote Mac for the account with which you authenticated. You can perform a similar routine and target your current Mac, by using “localhost” or the loopback IP address 127.0.0.1” as the computer name in the URL.

This approach has its uses, such as creating and running scripting routines on a main central Mac that you can have execute on any remote Mac that you target—an approach that may be particularly useful for server administrators. However, with the latest security updates, some systems may no longer accept communication by the eppc protocol, breaking this approach either in AppleScripts or in programs that use Remote Apple Events.

Recently MacIssues reader Matt S. wrote in about his ongoing inability to control various Macs using eppc, and in testing the above script for activating the Finder, found that the following conditions fairly consistently fail:

• Either OS X 10.8 or 10.9 Server communicating to 10.6 through 10.9
• OS X 10.10 Server communicating to 10.8 and 10.9

This suggests some detail implemented with the security update in OS X Server versions 10.8 and 10.9 is breaking this version’s ability to communicate with other Macs using eppc. Oddly, the reverse is true for OS X 10.10, where it will receive communication from these versions of OS X, but not be able to send communications to 10.8 or 10.9. Either way, the problem is linked to the latest security updates Apple has released.

The suspicion here is that with the release of Security Update 2015-002, Apple revoked the way OS X handles some network encryption routines in order to close a few security holes in OS X (including the FREAK vulnerability in the Secure Transport layer), and in doing so interrupted the system’s ability to use Remote Apple Events. Unfortunately, it is somewhat unclear how to overcome this problem, so if it is affecting you, then you have two options:

1. Create a version of your scripts to only target the local machine, and then deploy them.
2. Restore your Macs to a backup before having installed the security updates.