Trying to configure Akeeba Backup to use the Post-processing engine set to Dropbox fails.
Authentication - Step1 opens a pop up window with an error at the bottom
Dropbox Authentication Error invalid_grantDropbox reported that you did not log in correctly or did not grant Akeeba Backup the permission to access your account.
If I click on "Complete Dropbox authentication" in the pop up window I get kicked out of Joomla.