What causes "Socket input is shutdown" in spring-projects/spring-boot?

Do not call shutdownInput() if further reads are needed on this socket.

spring-projects/spring-boot · error · SocketException

Socket input is shutdown

Error message

Socket input is shutdown

What it means

The third state check in UnixDomainSocket.getInputStream: if isInputShutdown() is true, throw SocketException('Socket input is shutdown'). This mirrors java.net.Socket.shutdownInput() semantics — a half-close for the read direction. Once shutdownInput() has been called, the input stream cannot be obtained again on the same socket.

Source

Thrown at buildpack/spring-boot-buildpack-platform/src/main/java/org/springframework/boot/buildpack/platform/socket/UnixDomainSocket.java:65

	private final SocketAddress socketAddress;

	private final SocketChannel socketChannel;

	private UnixDomainSocket(String path) throws IOException {
		this.socketAddress = UnixDomainSocketAddress.of(path);
		this.socketChannel = SocketChannel.open(this.socketAddress);
	}

	@Override
	public InputStream getInputStream() throws IOException {
		if (isClosed()) {
			throw new SocketException("Socket is closed");
		}
		if (!isConnected()) {
			throw new SocketException("Socket is not connected");
		}
		if (isInputShutdown()) {
			throw new SocketException("Socket input is shutdown");
		}

		return Channels.newInputStream(this.socketChannel);
	}

	@Override
	public OutputStream getOutputStream() throws IOException {
		if (isClosed()) {
			throw new SocketException("Socket is closed");
		}
		if (!isConnected()) {
			throw new SocketException("Socket is not connected");
		}
		if (isOutputShutdown()) {
			throw new SocketException("Socket output is shutdown");
		}

		return Channels.newOutputStream(this.socketChannel);

View on GitHub (pinned to 270dfe353f)

Solutions

Do not call shutdownInput() if further reads are needed on this socket.
Open a new socket (UnixDomainSocket.get(path)) for the next read.

Example fix

// before
socket.shutdownInput();
socket.getInputStream().read(); // throws "Socket input is shutdown"
// after: open a fresh socket for the next read
Socket next = UnixDomainSocket.get(path);
next.getInputStream().read();

Defensive patterns

Strategy: validation

Validate before calling

// Guard before obtaining a stream
if (socket.isInputShutdown()) {
    socket = UnixDomainSocket.get(path); // reopen for a fresh input stream
}
InputStream in = socket.getInputStream();

Try / catch

try {
    socket.getInputStream();
} catch (java.net.SocketException ex) {
    if ("Socket input is shutdown".equals(ex.getMessage())) {
        socket = UnixDomainSocket.get(path); // reopen and retry once
    } else throw ex;
}

Prevention

Do not call shutdownInput() on sockets that need further reads.
Open a fresh socket per request/response cycle rather than reusing half-closed sockets.
Audit protocol implementations that half-close after sending for correctness.

When it happens

Trigger: getInputStream() is called after shutdownInput() was invoked on the socket (half-close for reading).

Common situations: A protocol layer that calls shutdownInput() after sending a request and then tries to read a response; reuse of a half-closed socket for a second request; test code invoking shutdownInput().

Related errors

AI-assisted analysis of spring-projects/spring-boot@270dfe353f (2026-08-11). Data as JSON: /api/errors/69195dee725dd1a0. Report an issue: GitHub.