But, first, let me define the problem.
You can run REST API calls to the management interface but cannot login via the management UI.
So, what did you do?
You did three things
Bang, you're in deep trouble!
So, what gives?
You are asked for a sysadmin user/password when you install Apigee on-premise (scott/tiger comes to mind). Now, these credentials are encrypted and stored in config files, config stores, and LDAP.
But, later when you use the platform you are added as a USER with a specific role (org admin, ops admin, etc.). This information is also stored in LDAP.
So, now when you change the password in the UI you will change the data stored in LDAP. But, that doesn't change the config files and stores!!!
Yeah, oh crapola!
So, like I said, don't use the same email address/pwd as a system admin account and as a user of the platform. I know you're thinking who would ever do that! Errr...yeah...good luck with that!
I recall doing something like that at one point. I think I fixed it by using the "chpasswd-system.sh" script in bin directory.
And, that was after a lot of pain, right? BTW, does not change config files across a multi-node deployment?
And ... if you do find yourself in this unfortunate situation, the following links may be of great help:
https://community.apigee.com/articles/2138/how-to-reset-a-lost-sysadmin-password-on-apigee-ed.html
https://community.apigee.com/articles/1916/opdk-how-to-manually-update-ui-credentials-for-acc.html