Description of problem:

Bug https://bugzilla.redhat.com/show_bug.cgi?id=2106473 , doesn't cover all the possible reasons that could raise the following error.
Could not import the archive.: undefined method 'content_url' for nil:NilClass".

The fix only validated whether a product is available in the disconnected Satellite or not, but it doesn't validate the contents of the product are available.

For example, "Red Hat Satellite 6.15" content is missing for the "Red Hat Satellite" product because user imported/refreshed the manifest before the content is released.

Therefore, user will need to re-import the manifest to the disconnected Satellite to get the latest contents.