ASK HN :Problems with 3rd party code integrations

This is a high level query, I want to learn from the developers here about their experience with 3rd party code integrations. These can be working with open source projects or commercial APIs/SDKs. I have worked on multiple 3rd party integrations in the past including Payments, Fintech, E-commerce, security , AI and analytics from a product/business perspective. The problems that I saw developers working on these were poor documentation, getting lost in trial and errors, miscommunication between dev teams, errors in security implementation, version related issues, connectivity related problems. Do share your experience.