You can obtain a seeddb.bin through several methods, depending on your setup:

Without the correct seed entry, a title will fail to decrypt — typically resulting in a black screen, error message, or crash on launch. The seed database allows the 3DS to:

: If the file is not exactly the correct format or has been tampered with, decryption will fail even if the seed is technically present .

The seeddb.bin file is an essential database for the Nintendo 3DS community, used to decrypt and install games released after mid-2015. This "full" database contains unique encryption seeds required to process modern 3DS titles on both hardware and emulators. Understanding the 3DS Seed Database

Here's a simplified overview of how SeedDB.bin works: