square/okhttp · error · IOException

Unexpected code

Error message

Unexpected code 

What it means

Thrown in the PostStreaming recipe: `if (!response.isSuccessful()) throw new IOException("Unexpected code " + response)`. It streams generated markdown (a prime-factorization table) to GitHub's markdown/raw endpoint via a custom RequestBody whose writeTo writes to the sink on demand. The guard fires when GitHub answers non-2xx after the stream completes.

Solutions

1. Check response.code() and the body for GitHub's error message.
2. If a proxy rejects chunked uploads, buffer the body and set a Content-Length (use RequestBody.create with bytes).
3. Add a token header to avoid 403 rate limiting.
4. Confirm the markdown/raw endpoint still exists; switch to /markdown if needed.

Example fix

// before
if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);

// after
if (!response.isSuccessful()) {
  throw new IOException("markdown/raw HTTP " + response.code() + ": " + response.body().string());
}

// If a proxy rejects chunked uploads, set a Content-Length by buffering.
// Otherwise branch on status after streaming completes.
if (!response.isSuccessful()) { /* code + body */ return; }

static boolean streamed(Response r) { return r.isSuccessful(); }

try {
  // call (streamed)
} catch (IOException e) {
  // includes 'Unexpected code' (HTTP status) and transport errors mid-stream
}

When it happens

Trigger: POST https://api.github.com/markdown/raw with a streamed markdown body returns 404 (endpoint gone), 403 (rate limit), 400 (body too large or malformed), or 5xx. Because the body is streamed without Content-Length, some servers/proxies reject it; GitHub historically supports chunked markdown/raw but may change.

Common situations: GitHub deprecating markdown/raw; rate limit; a proxy that requires Content-Length rejecting the chunked POST; generating an unexpectedly huge body (primes up to 997 is small, but the pattern scales).

Related errors

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

AI-assisted analysis of square/okhttp@91a8b34c6f (2026-08-10). Data as JSON: /api/errors/5027c105b57a619a. Report an issue: GitHub.

Appendix: 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();
  }
}

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