Launchctl says plist is invalid, plutil says it's OK
The first few lines should be

&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"&gt;
&lt;plist version="1.0"&gt;
&lt;dict&gt;


Your file (as well as the one in the linked answer) is missing the &lt;plist version="1.0"&gt; part.