After few ours of struggle we found a solution. Actually it was an issue of cookies being blocked by Internet Explorer. We all know that laravel app creates certain cookies on the front end. This was blocked by Internet Explorer hence Ajax requests were not working as it was unable to find cookies. First of let me explain what exactly was the issue and then we will look for solution.
In this case, when cookies are blocked, session identifier is not sent, and the target script throws a 'session not found' error.
header('P3P: CP="This site does not have a p3p policy."');
And that's it it will solve the problem.
You can get more information about P3P policy from below link.