What causes "Invalid port number" in quarkusio/quarkus?

Pass a valid port in the 1-65535 range (typically 80, 443, 3128, 8080, etc.)

quarkusio/quarkus · error · IllegalArgumentException

Invalid port number

Error message

Invalid port number

What it means

Thrown by QuarkusRestClientBuilder.proxyAddress when the port is outside the valid range 1-65535. Proxy ports must be a valid TCP port, so zero, negative values and values above 65535 are rejected with IllegalArgumentException.

Source

Thrown at extensions/resteasy-classic/resteasy-client/runtime/src/main/java/io/quarkus/restclient/runtime/QuarkusRestClientBuilder.java:181

    public RestClientBuilder queryParamStyle(QueryParamStyle queryParamStyle) {
        this.queryParamStyle = queryParamStyle;
        return this;
    }

    @Override
    public RestClientBuilder header(final String name, final Object value) {
        headers.add(Objects.requireNonNull(name, "A header name is required."),
                Objects.requireNonNull(value, "Value for header is required."));
        return this;
    }

    @Override
    public RestClientBuilder proxyAddress(String host, int port) {
        if (host == null) {
            throw new IllegalArgumentException("proxyHost must not be null");
        }
        if (port <= 0 || port > 65535) {
            throw new IllegalArgumentException("Invalid port number");
        }
        this.proxyHost = host;
        this.proxyPort = port;
        return this;
    }

    @Override
    public RestClientBuilder baseUrl(URL url) {
        try {
            baseURI = url.toURI();
            return this;
        } catch (URISyntaxException e) {
            throw new RuntimeException(e.getMessage());
        }
    }

    @Override
    public RestClientBuilder baseUri(URI uri) {

View on GitHub (pinned to e1c734241f)

Solutions

Pass a valid port in the 1-65535 range (typically 80, 443, 3128, 8080, etc.)
Fix the proxy-address config value to a valid host:port pair
Do not use sentinel values like 0 or -1 to disable the proxy — simply don't call proxyAddress

Example fix

// before
builder.proxyAddress("proxy.corp", 80800); // IllegalArgumentException: Invalid port number
// after
builder.proxyAddress("proxy.corp", 8080);

Defensive patterns

Strategy: validation

Validate before calling

if (port < 1 || port > 65535) {
    throw new IllegalArgumentException("Proxy port out of range: " + port);
}

Type guard

static boolean isValidPort(int p) { return p > 0 && p <= 65535; }

Try / catch

try {
    builder.proxyAddress(host, port);
} catch (IllegalArgumentException e) {
    if (e.getMessage().equals("Invalid port number")) {
        log.error("Bad proxy port: {}", port);
    }
    throw e;
}

Prevention

Never use 0 or -1 as a 'disabled' sentinel port — omit the proxyAddress call instead
Parse proxy ports with Integer.parseInt and range-check before use
Validate proxy-address host:port config values at startup

When it happens

Trigger: Calling builder.proxyAddress(host, 0), a negative port, or a port parsed from a truncated/garbled config value; port > 65535 from an int overflow of a concatenated string; passing -1 as a 'no proxy' sentinel.

Common situations: Using -1 or 0 as a default 'unset' port constant; config property proxy-address missing the port part so the parsed default leaks through; typos like 80800.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/d6441b08459df405. Report an issue: GitHub.