I am developing an Angular application running on a NodeJS server and I am using Kinvey for data store: https://devcenter.kinvey.com/nodejs
When I log in from one browser, everything works correctly, but when I log in from a second browser without logging out from the first one, I get an error message that says there cannot be more than one Active User. The app still runs on localhost.
Are multiple accounts allowed when using Kinvey ActiveUser on NodeJS servers?
There can only be one active user at a time, but that doesn't mean one per the entire application. It really depends on how you are handling your active user. If this is something where you are trying to just make a generic data call and don't want to require the user to have to log in, you'd want to set up a generic user for the app or use an implicit user. In all cases, you can check if there is an existing user prior to trying to log in a new user.
I wrote a long tutorial about the various kinds of users that you can find here: https://www.progress.com/blogs/understanding-users-kinvey