quarkusio/quarkus · error · IllegalStateException

getting all the contents of a MultiByteHttpData is not suppo

Error message

getting all the contents of a MultiByteHttpData is not supported

What it means

get() returns the entire part content as a byte[] in standard Netty HttpData. MultiByteHttpData is a streaming adapter whose buffer may not hold all bytes at once and which requests more data lazily from the upstream Multi; materializing the whole content would violate its design, so get() throws IllegalStateException.

Source

Thrown at independent-projects/resteasy-reactive/client/runtime/src/main/java/org/jboss/resteasy/reactive/client/impl/multipart/MultiByteHttpData.java:167

    @Override
    public void setContent(File file) throws IOException {
        throw new IllegalStateException("setting content of MultiByteHttpData is not supported");
    }

    @Override
    public void setContent(InputStream inputStream) throws IOException {
        throw new IllegalStateException("setting content of MultiByteHttpData is not supported");
    }

    @Override
    public void delete() {
        // do nothing
    }

    @Override
    public byte[] get() throws IOException {
        throw new IllegalStateException("getting all the contents of a MultiByteHttpData is not supported");
    }

    @Override
    public ByteBuf getByteBuf() {
        throw new IllegalStateException("getting all the contents of a MultiByteHttpData is not supported");
    }

    /**
     * check if it is possible to read the next chunk of data of a given size
     *
     * @param chunkSize amount of bytes
     * @return true if the requested amount of bytes is ready to be read or the Multi is completed, i.e. there will be
     *         no more bytes to read
     */
    public boolean isReady(int chunkSize) {
        return done || buffer.readableBytes() >= chunkSize;
    }

View on GitHub (pinned to e1c734241f)

Solutions

Read content incrementally via getChunk(int) only after isReady(chunkSize) returns true, as PausableHttpPostRequestEncoder does.
If you need full bytes, send a byte[]-based part instead of a Multi<Byte> streaming part.
Collect the upstream Multi<Byte> itself (e.g. Multi collect().in(byte[])) before sending rather than pulling from the adapter.
Do not write generic code that assumes get() is safe on every FileUpload; branch on the concrete type.

Example fix

// before
byte[] all = multiByteHttpData.get();
// after
ByteBuf chunk = multiByteHttpData.getChunk(BUFFER_SIZE); // after isReady(BUFFER_SIZE)
byte[] part = new byte[chunk.readableBytes()];
chunk.readBytes(part);

Defensive patterns

Strategy: type-guard

Validate before calling

byte[] safeGet(InterfaceHttpData data) {
    if (data instanceof MultiByteHttpData) {
        throw new IllegalArgumentException("Read streaming parts via getChunk(), not get()");
    }
    return data.get();
}

Type guard

boolean supportsFullGet(InterfaceHttpData data) {
    return !(data instanceof MultiByteHttpData);
}

Try / catch

try {
    byte[] all = data.get();
} catch (IllegalStateException e) {
    if (e.getMessage() != null && e.getMessage().contains("not supported")) {
        // drain incrementally via isReady()/getChunk()
    } else {
        throw e;
    }
}

Prevention

Read streaming parts only via isReady(int)/getChunk(int).
Use byte[] parts if you need whole-content access.
Collect the source Multi<Byte> before sending if you need the full payload.
Don't assume get() works on every FileUpload implementation.

When it happens

Trigger: Calling get() on a MultiByteHttpData, e.g. from debugging/logging code, generic InterfaceHttpData processors, or a decoder that drains completed uploads into memory.

Common situations: Inspecting sent multipart bodies in tests or interceptors; post-request processing of response/file-upload structures that call get() uniformly; tools that snapshot multipart parts for retries.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/540ed6348b4b8264. Report an issue: GitHub.