This is something anyone who owns an iPhone or recent Android mobile device should be aware of. Biometrics such as fingerprint sensors are generally considered more secure than password protection, but they have a high potential for failure. It happened to me.
Last Monday, I found that Signal on my Android phone had locked up. I was locked out and completely unable to access my messages or my contacts without reinstalling. The problem is, biometrics sensors can break or be disabled. Repair is much more difficult than resetting a password.