How to disable primary key check in FireBird?

Question

Backup

So there was a table, it had a random NULL field, then when the table was upgraded, this field became PrimaryKey and began to be filled with values, but the old records remained with NULL, and now FireBird, when trying to restore the database from a backup, swears at the fact that the PrimaryKey is not may be null. How to disable check when restoring a database??