I have a launch agent on a remote machine which runs Yosemite. The LaunchAgent is saved to ~/Library/LaunchAgents/
and I am the owner:
$ ls -l ~/Library/LaunchAgents
-rw-r--r--@ 1 me staff 803 Jan 13 15:13 org.my.custom.plist
$ ls -l@ ~/Library/LaunchAgents/org.my.custom.plist
-rw-r--r--@ 1 me staff 803 Jan 13 15:13 /Users/me/Library/LaunchAgents/org.my.custom.plist
com.apple.TextEncoding 15
When logging in via SSH (as that particular user), attempting to load the file produces the following exchange:
$ launchctl load ~/Library/LaunchAgents/org.my.custom.plist
/Users/me/Library/LaunchAgents/org.my.custom.plist: Operation not permitted
Why is the operation not permitted when I'm the owner? It works fine under Sierra.