quarkusio/quarkus · error · ErrorDataDecoderException

No 'Content-Type' header present.

Error message

No 'Content-Type' header present.

What it means

This ErrorDataDecoderException is thrown by QuarkusMultipartResponseDecoder's constructor when the HTTP response it is asked to decode has no Content-Type header. A multipart decoder cannot know the boundary string or media type without it, so construction fails immediately and the response body cannot be decoded.

Source

Thrown at independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/multipart/QuarkusMultipartResponseDecoder.java:217

     *        the request to decode
     * @param charset
     *        the charset to use as default
     * @throws NullPointerException
     *         for request or charset or factory
     * @throws ErrorDataDecoderException
     *         if the default charset was wrong when decoding or other
     *         errors
     */
    public QuarkusMultipartResponseDecoder(QuarkusMultipartResponseDataFactory factory, HttpClientResponse response,
            Charset charset) {
        this.response = checkNotNull(response, "request");
        this.charset = checkNotNull(charset, "charset");
        this.factory = checkNotNull(factory, "factory");
        // Fill default values

        String contentTypeValue = this.response.headers().get(HttpHeaderNames.CONTENT_TYPE);
        if (contentTypeValue == null) {
            throw new ErrorDataDecoderException("No '" + HttpHeaderNames.CONTENT_TYPE + "' header present.");
        }

        String[] dataBoundary = getMultipartDataBoundary(contentTypeValue);
        if (dataBoundary != null) {
            multipartDataBoundary = dataBoundary[0];
            if (dataBoundary.length > 1 && dataBoundary[1] != null) {
                try {
                    this.charset = Charset.forName(dataBoundary[1]);
                } catch (IllegalCharsetNameException e) {
                    throw new ErrorDataDecoderException(e);
                }
            }
        } else {
            destroy();
            throw new ErrorDataDecoderException("Unable to parse multipart response - No delimiter specified");
        }
        currentStatus = MultiPartStatus.HEADERDELIMITER;

View on GitHub (pinned to e1c734241f)

Solutions

1. Fix the server (or proxy) so multipart responses always include a Content-Type header such as multipart/mixed; boundary=...
2. Check client-side filters/interceptors for code that removes or replaces the Content-Type header
3. Verify the decoder is only invoked for responses that are actually multipart; check isMultipart() before constructing
4. Catch ErrorDataDecoderException and fall back to reading the raw response body

Example fix

// before
// decoder constructed for any response
QuarkusMultipartResponseDecoder decoder = new QuarkusMultipartResponseDecoder(response, factory, charset);
// after
if (response.headers().contains(HttpHeaderNames.CONTENT_TYPE)) {
    QuarkusMultipartResponseDecoder decoder = new QuarkusMultipartResponseDecoder(response, factory, charset);
} else {
    // handle non-multipart / malformed response
}

if (!response.headers().contains(HttpHeaderNames.CONTENT_TYPE)) {
    throw new IllegalArgumentException("Response is missing Content-Type; cannot decode multipart");
}
String ct = response.headers().get(HttpHeaderNames.CONTENT_TYPE);
if (!ct.startsWith("multipart/")) { /* route to a non-multipart decoder */ }

try { decoder = new QuarkusMultipartResponseDecoder(response, factory, charset); } catch (ErrorDataDecoderException e) { /* fall back to raw body */ }

When it happens

Trigger: Constructing a QuarkusMultipartResponseDecoder (or receiving a multipart response through the reactive client) where response.headers().get(HttpHeaderNames.CONTENT_TYPE) returns null — i.e. the server response lacks a Content-Type header entirely.

Common situations: A misbehaving or hand-rolled server/proxy strips the Content-Type header; a custom Netty pipeline feeds a non-multipart or malformed response into the multipart decoder; interceptors or response filters rewrite headers and drop Content-Type.

Related errors

• Needs a boundary value
• Cannot create a Encoder if request is a TRACE
• Illegal charset in multipart response Content-Type (wrapped)
• Unable to parse multipart response - No delimiter specified
• QuarkusMultipartResponseDecoder was destroyed already

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/f3c6c7cd51814e26. Report an issue: GitHub.