The worst is when project B is a closed source project. I have such an open-source project A that interacts with such a project B. That is the worst. Then I get a bug report, project B got a new version and your project A does not work anymore. Fix it! Then I ask what was changed in the new version of project B. Then they say, they do not know. Then I ask the company of project B. They do not respond. Then I get another email from a user, you need to fix it for the new project B version. Then I send 5 emails to the company of project B. Then they respond, "we do not support project A". And I do not have access to project B myself
