YSOD/server error when clicking on Bell Schedule Page at the school level

Environment

Scheduling Type: Flex

Conversion from type "DBNull" to type "String" is not valid.

Cause

NULL value in ST field in BSD table for a specific KY.

Resolution

Identify the BSD record with a NULL in ST

EXAMPLE

SELECT * FROM BSD
WHERE ST IS NULL

Update the BSD.ST field to a valid time 

EXAMPLE

UPDATE BSD
SET ST = '1900-01-01 07:00:00:000'
WHERE KY = 3
AND ST IS NULL