Problems when running composer update

[spitfire64]

When I run composer update (edit: ...on my live server...) to install a completely different package I am promted to give my Flux usernamne and password:

    Authentication required (composer.fluxui.dev):
      Username: my-flux-username
      Password: my-flux-password

When I do so, I get this:

In AuthHelper.php line 216:
  Invalid credentials (HTTP 401) for 'https://composer.fluxui.dev/packages.js
  on', aborting.

Edit: I just moved my project from www.my-old-appname to www.my-new-appname