Keep the HTTP status, safe error code, request reference, endpoint, and time with timezone. Explain the action you intended and whether it failed consistently or only once. A browser or proxy can return a different failure from the API itself.
Share the smallest redacted request and response that explains the problem. Remove authorization headers, tokens, phone numbers, private links, and unrelated message content. For an uncertain write, check the resulting resource before repeating it. A timeout is not proof that the action did not happen.