I failed due to having too complex a password.  Here is what I learnt on the way, though.

  1. CherryTree encrypted databases are a 7z encrypted archive
    So you need to crack the 7z archive.
  2. Get the password hash from the 7z file
    Use 7z2hashcat
  3. Use HashCat to attach the password hash.

Why did I fail?

I used a long, complex passphrase, and the time to crack that is measured in years.

LostMyPass – password recovery service
Crackstations – Password Cracking Dictionary