I started getting this error very recently. I believe it’s linked to a recent email that I got regarding password requirement changes:
Heroku will start resetting user account passwords today, May 4, 2022, as mentioned in our previous notification. We recommend that you reset your user account password in advance here and follow the best practices below:
- Minimum of 16 characters
- Minimum complexity of 3 out of 4: Uppercase, Lowercase, Numeric, Symbol
- Don’t just add a letter or a 1 digit number to the existing password while changing
- Passwords may not be duplicated across accounts
As mentioned elsewhere, resetting my password and ensuring LastPass included symbols resolved it.