WT -> SEO -> Import New Rates -> Life -> Server error is displaying while exporting rate.

1] Login to the application on local environment using following URL:
https://wt-stage.harbinger.in
2] From Home page search and select a company for which testing needs to be carried out using "Search Company" section.
3] Click on "Ben Admin" menu.
4] Click on "Customizer" icon from left navigation menu.
5] Click on "Rates" link which is submenu of "Customizer", user gets navigate to "Rates" details page.
6] Click on "Import" button displaying at top right hand side of the "Rates"page, the "Rate Import" window gets popped up.
7] Click on "Add New Rates" tab.
8] Download the Life benefit template.
9] Mentioned rate name start/end date
10] Browse and upload the rate file.
11] Select the newly imported Life rate and click on Export button.

Actual Result:
"Server encountered an internal error..." pop message is displaying.
Expected Result:
Life rate should be get exported without any error.
Refer attached screen shot and log for more details.