Migration procedure from v10 to v11(Invalid variable type)

We are considering migration from v10 (java) to v11 (.net).

Currently, we are verifying the application migration from v10 (java) to v11 (.net), but after migration, the following error occurred when testing the application.

An invalid type error occurs when passing Null information of the search result to Integer Structure after SQL search.

It is said that there are no bugs related to the migration from v10 (java) to v11 (.net).
please tell me the migration procedure that does not cause the above bugs.

Just to remove from unanswered, reply made here.