Time Machine backup not working since updating to Catalina

When I updated to Catalina and Time Machine tried to backup I got a message that I should have taken a screenshot. It was something I haven't seen before. So to try to fix it I went into the Time Machine preferences and removed the disk and then tried to choose it again.

When I choose the same disk and check encrypt backup (it was encrypted before and I know what my password is) it will then ask if I want to start over with a new backup, choose a different disk, or use the existing backup. I want to use the existing one so I choose that. It then asks me to enter the password for the backupbundle. When I enter what I know is what I chose when I set it up it says that the password is incorrect. I've even tried every other possible password that I could have used and it says the same thing.

I cannot get it to use the existing backup and I don't believe it is because I have the wrong password. What can I do?