Dear i m getting error as under:-
(1/1) UndefinedMethodException
Attempted to call an undefined method named "getUsageIndex" of class "Symfony\Component\HttpFoundation\Session\Session".
in AbstractSessionListener.php line 39
at AbstractSessionListener->onKernelRequest(object(GetResponseEvent), 'kernel.request', object(TraceableEventDispatcher))in WrappedListener.php line 115
at WrappedListener->__invoke(object(GetResponseEvent), 'kernel.request', object(TraceableEventDispatcher))in EventDispatcher.php line 212
at EventDispatcher->doDispatch(array(object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener), object(WrappedListener)), 'kernel.request', object(GetResponseEvent))in EventDispatcher.php line 44
at EventDispatcher->dispatch('kernel.request', object(GetResponseEvent))in TraceableEventDispatcher.php line 143
at TraceableEventDispatcher->dispatch('kernel.request', object(GetResponseEvent))in HttpKernel.php line 127
at HttpKernel->handleRaw(object(Request), 1)in HttpKernel.php line 68
at HttpKernel->handle(object(Request), 1, false)in Kernel.php line 200
at Kernel->handle(object(Request), 1, false)in index.php line 86
After upgrade i enabled debug mode and above lines are now showing at backoffice page.
So please help hows i can clear this error