Delete VTN and Flowlist failed when i removed from VTN/VBR Flowfilter configurations

When i cloned latest Stable/Beryllium and created VTN/VBR flowfilter configurations. Issue faced while i delete VTN and Flowlist.

To reproduce issue:

1) Create VTN, VBR, VBRIF, Flowlistentry, VBRFlowfilter.
2) Test Ping.
3) Delete VTN and Flowlist. (retuns internal server error '500' for delete VTN and returns '400' for delete flowlist)

The above are the steps which is tested using CSIT.

Attached log