What is the passphrase for opening a BitLocker disk on Ubuntu?

When prompted for your passphrase, you need to enter your BitLocker recovery key. It looks something like:

318846-013959-335082-562221-588214-181456-652498-331848

How to find your BitLocker recovery key:

When you enabled BitLocker full disk encryption on your Windows partition, you were prompted to save a recovery key on an external USB stick, or somewhere else. The file is a text file named something like BitLocker Recovery Key ....txt. If you can still log in to Windows, you can create this recovery key again. For more information, see: Finding your BitLocker recovery key in Windows