Persistence using Http cookie insert

Hi,

 

 

We are having the issue with virtual server configured with persistence profile - Cookie (Http cookie insert method) and expiration set to session cookie (default).

 

 

Its been observed , for some request the F5 cookie is not appended and causing internal server error.

 

 

 

I am running bigip version - 10.2.0.

 

 

Any thoughts why there are no cookies appended for some of the requests.