Someone has created a session cookie that is unusually large. This is generally not a good idea from an architectural perspective. AppMon is smart enough to know that certain objects are just not worth capturing given their size. If there's nothing in the cookie that you need, then you can likely ignore this message. If you're trying to capture something in this cookie, you can try increasing the value of the allowed strings capture size for your profile, but i'm not positive this will resolve this warning. An alternate idea is to open a support case and request guidance.