Created Unassigned: ExecuteReader requires an open and available Connection. The connection's current state is open. [1250]

Hi ,
After updating Generic Unit of Work & (Extensible) Repositories Framework to latest version in my old project(latest version works fine) i got this error when multiple request comes at a same time to my website.(When traffic of my web site goes high).
that is urgent situation . what is a problem ?
I am waiting for ur help ....
Thanks