Laravel Incorrect date value error

I`m trying to create page for add user details to database via form values.it gives me this error when i press the submit button.

Here is my migration field.

 $table->date('gce_ol_year');

Here is the relevant form attribute

     <div class="form-group">
        <label>GCE(O/L) Year:</label>
    <input class="form-control" name="gce_ol_year" type="month" value="2011-08" id="example-month-input">
  </div>

Here is the relevant controller attribute

$item ->gce_ol_year = $request ->gce_ol_year;

Can anyone help me to fix this error? Thanks.

via Dasun