Siri on my Late 2012 iMac stopps responding to system related queries.
For example
"How fast is my mac?"
I would get
"Sorry something is wrong, try again later"
This is easily worked around by killing the siri process. Once you kill it it will auto-restart and continue working as normal.
rdar://26980032
A workaround is as follows.
From a terminal find the pid of the Siri process.
`ps aux | grep Siri`
Kill the siri process
`kill -9 <pidofsiri>`
Try and perform siri intention again and siri will respond as it should.
