square/okhttp · error · IOException

Unexpected code

Error message

Unexpected code 

What it means

Recipe-level guard after POSTing a streaming RequestBody (an anonymous subclass that writes generated markdown prime factorisations to the BufferedSink) to GitHub's markdown/raw endpoint. If the response is non-2xx, java.io.IOException("Unexpected code " + response) is thrown. The body is produced on-demand during writeTo(), so a writeTo() IOException (e.g. the connection is closed mid-upload) surfaces from execute(), not this line.

Source

Thrown at samples/guide/src/main/java/okhttp3/recipes/PostStreaming.java:61

        }
      }

      private String factor(int n) {
        for (int i = 2; i < n; i++) {
          int x = n / i;
          if (x * i == n) return factor(x) + " × " + i;
        }
        return Integer.toString(n);
      }
    };

    Request request = new Request.Builder()
        .url("https://api.github.com/markdown/raw")
        .post(requestBody)
        .build();

    try (Response response = client.newCall(request).execute()) {
      if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

      System.out.println(response.body().string());
    }
  }

  public static void main(String... args) throws Exception {
    new PostStreaming().run();
  }
}

View on GitHub (pinned to 4fc0831380)

Solutions

1. Verify contentType() returns exactly text/x-markdown; charset=utf-8.
2. Inspect response.code() and rate-limit headers.
3. Authenticate to GitHub to lift the cap.
4. Write a small, deterministic test payload first to isolate content vs. transport issues.

Example fix

// before
try (Response response = client.newCall(request).execute()) {
  if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
  ...
}

// after
try (Response response = client.newCall(request).execute()) {
  if (!response.isSuccessful()) {
    throw new IOException("GitHub markdown/raw " + response.code()
        + " (contentType=" + MEDIA_TYPE_MARKDOWN + ")");
  }
  ...
}

// Ensure the streaming body's content type matches what the endpoint expects
MediaType mediaType = MediaType.get("text/x-markdown; charset=utf-8");
// keep contentType() returning exactly this; authenticate the request:
Request request = new Request.Builder()
    .url("https://api.github.com/markdown/raw")
    .header("Authorization", "Bearer " + token)
    .header("User-Agent", "MyApp/1.0")
    .post(streamingBody)  // contentType() == mediaType
    .build();

try (Response response = client.newCall(request).execute()) {
  if (!response.isSuccessful()) {
    if (response.code() == 415) throw new UnsupportedMediaTypeException("Use text/x-markdown; charset=utf-8");
    if (response.code() == 403) throw new RateLimitedException(response.header("X-RateLimit-Reset"));
    throw new HttpException(response.code(), response.message());
  }
}

When it happens

Trigger: POST https://api.github.com/markdown/raw with a chunked streaming body. Reaches this line when the body was sent successfully but GitHub returned 4xx/5xx: 403 (rate limit), 415 (media type mismatch — must be text/x-markdown), 404/410 (endpoint retired), 400 (malformed body).

Common situations: Wrong content-type in contentType() (must match the .header or the endpoint's expectation); GitHub rate limit on the unauthenticated markdown API; a writeTo() bug producing an invalid UTF-8 sequence (would throw earlier).

Related errors

• Unexpected code
• Unexpected code
• Unexpected code
• Unexpected code
• Unexpected code

AI-assisted analysis of square/okhttp@4fc0831380 (2026-08-04). Data as JSON: /data/errors/5027c105b57a619a.json. Report an issue: GitHub.