Hi Nikhil,
I saw that the other day on one of our demo sites. I'm not 100% certain what the cause was but it was linked to one of the performance activities (turning on debugging let me see where the issue was).
I just deleted that performance activity and it went away (it was a demo site and I was looking for a quick fix so didn't into it much more closely)
I have a feeling it has something to do with the server setup. When I looked for that error in google it talked about xdebug being turned on in the php config, so maybe start by checking if that's turned on for you.
David