For years I've used the heroku-accounts plug-in to easily switch between different Heroku accounts when using the Heroku CLI toolbelt.
As of about a month ago, however, it has stopped working. Whenever I switch over to an account and try to do something, like log in to Rails console, I get the error "Invalid credentials provided." It then prompts me to type a letter, which opens a browser, which then prompts me to log in. In other words, I have to re-log in whenever I switch accounts, which is exactly what the plug in is supposed handle.
(heroku-accounts version = 1.1.7)
Thanks to this thread from @Chris, I played around with removing and re-adding the accounts until I finally got it working.