Frontend Error: Value '00000000' violates facet information 'nullable=false'

[AnikethBR]

Type Frontend Error
Short Text Value '00000000' violates facet information 'nullable=false

We have an unmanaged entity in RAP where one key field is of type date which even if date is populated, we face the below error.
Value '00000000' violates facet information 'nullable=false'.

Request @SAP to solve this bug, since similar issue was reported by user 4 years ago still no solution was suggested

Similar question asked in 2022 still no answer

ABAP RESTful Application Programming Model  ABAP Development ABAP Development SAP Quality Issue Management SAP BTP ABAP environment 

[junwu]

are you sure your date is populated?

[AnikethBR]

I am sure that date is populated. Because I am selecting the existing data from db table KNVH which has key field of DATAB (Start of validity period for assignment) data element = DATAB_KH.

[junwu]

don't be so sure, debug please...