InvalidArgumentException

[gunjanp11]

Get below error when Bigcommerce APP launch:

InvalidArgumentException in Pimple.php line 78:
Identifier "session" is not defined.

in Pimple.php line 78
at Pimple->offsetGet('session') in index.php line 63
at {closure}(object(Request))
at call_user_func_array(object(Closure), array(object(Request))) in HttpKernel.php line 145
at HttpKernel->handleRaw(object(Request), '1') in HttpKernel.php line 66
at HttpKernel->handle(object(Request), '1', true) in Application.php line 538
at Application->handle(object(Request)) in Application.php line 515
at Application->run() in index.php line 206

Please help for solve this error.

Thanks