• I am on the latest Poetry version.
• I have searched the issues of this repo and believe that this is not a duplicate.
• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: MacOS 10.15.5
• Poetry version: 1.0.9
• Link of a Gist with the contents of your pyproject.toml file: https://gist.github.com/TimOrme/d69dc1f3ee6ce31cf93d154bd62d0595

Issue

If using a private repository to install external dependencies, it currently fails silently if that private repository rejects the request due to authentication issues. It would be good to instead at least log a warning to inform the user that the server didn't accept the request. Otherwise, it seems to indicate a problem with the packages actually being present.

 % poetry add mypackage

[ValueError]
Could not find a matching version of package mypackage

If mypackage is only present in the private repo, but they don't have credentials set properly, it should indicate to the user that there was auth error on that repo.