What does the "provider_err_nf" error mean when updating an extra?
The "provider_err_nf" error means that the package is not assigned to a package provider. This can happen when you removed a package provider to recreate it with a new API Key.
To fix it, click on "View Details" for the offending package. In the form that loads, choose the modmore.com package provider at "Provider", and save with the button in the top right. Click on "Close" to go back to the package list, and now you should be able of checking for updates again.
If you don't have a configured package provider, follow the instructions at API Keys.