Reading a session variable in CI3 that was set by CI4

Code:

<!-- New Program Details -->

        <div class="col-12 col-md-6 col-lg-4 col-xxl-3">

            <div class="form-group mb-3">

                <label for="institute" class="mb-2">Institute</label>

                <?php $institutes = $appLib->getInstituteList(); ?>

                <?= form_dropdown('institute', $institutes, '', 'id="institute" class="custom-select-2 mb-2" data-width="100%" required ') ?>

                <span class="text-capitalize error-span text-danger ms-1 my-2 d-none"></span>

            </div>

        </div>

        <div class="col-12 col-md-6 col-lg-4 col-xxl-3">

            <div class="form-group mb-3">

                <label for="degree" class="mb-2">Degree</label>

                <?php $degrees = $appLib->getDegreeList(); ?>

                <?= form_dropdown('degree', $degrees, ' ', 'id="degree" class="custom-select-2 mb-2" data-width="100%" required') ?>

                <span class="text-capitalize error-span text-danger ms-1 my-2 d-none"></span>

            </div>

        </div>

Code:

function getDegreeList(inst_id) {

 $.ajax({

 url : base_url + 'app/getDegreeList',

 type: 'POST',

 data: {#post_data},

  dataType:'html',

 success: function(data) {

 $('#selectTag').html(data);

 },

 error: function(xhr,status,err) {

 console.log('xhr => ',xhr,' Status => ',status,' Err => ',err);

 },

 });

 }