Over three days of building and publishing things through APIs I collected a set of error messages that have almost nothing written about them. For several of these, searching the exact string returns the vendor's own docs page that does not mention the error, and nothing else. So here they are, each with what actually causes it and what fixes it. Every one was reproduced and fixed on a real machine, not inferred. Assertion failed: !(handle->flags & UV_HANDLE_CLOSING), ...