quarkusio/quarkus · error · IllegalStateException

If ${prefix}.host is not set, then all of [${badValues}] mus

Error message

If ${prefix}.host is not set, then all of [${badValues}] must not be set either

What it means

When a quarkus.proxy.* configuration block does not set host, all other proxy settings (port, username, password, non-proxy-hosts, proxy-connect-timeout) are meaningless. ProxyConfigurationRecorder.build() throws IllegalStateException listing the offending keys instead of silently ignoring them.

Source

Thrown at extensions/proxy-registry/runtime/src/main/java/io/quarkus/proxy/runtime/ProxyConfigurationRecorder.java:78

                badValues.add("port");
            }
            if (config.credentialsProvider().name().isPresent()) {
                badValues.add("credentials-provider");
            }
            if (config.username().isPresent()) {
                badValues.add("username");
            }
            if (config.password().isPresent()) {
                badValues.add("password");
            }
            if (config.nonProxyHosts().isPresent()) {
                badValues.add("non-proxy-hosts");
            }
            if (config.proxyConnectTimeout().isPresent()) {
                badValues.add("proxy-connect-timeout");
            }
            if (badValues.length() > 0) {
                throw new IllegalStateException(
                        "If " + prefix + ".host is not set, then all of " + badValues + " must not be set either");
            }
            return Optional.empty();
        }

        if (config.port().isEmpty()) {
            throw new IllegalStateException("If " + prefix + ".host is set, " + prefix + ".port must also be set");
        }

        if (config.username().isPresent() != config.password().isPresent()) {
            throw new IllegalStateException(prefix + ".username and " + prefix + ".password must be both set or both unset");
        }

        Optional<String> username;
        Optional<String> password;
        if (config.username().isPresent() && config.password().isPresent()) {
            username = config.username();
            password = config.password();

View on GitHub (pinned to e1c734241f)

Solutions

Set quarkus.proxy."<name>".host to the proxy hostname
Or delete the orphaned sibling keys (port, username, password, non-proxy-hosts, proxy-connect-timeout) so the block is empty and skipped
Check for typos in the host property name

Example fix

// before
quarkus.proxy."x".port=8080
quarkus.proxy."x".non-proxy-hosts=localhost
// after
quarkus.proxy."x".host=proxy.example.com
quarkus.proxy."x".port=8080
quarkus.proxy."x".non-proxy-hosts=localhost

Defensive patterns

Strategy: validation

Validate before calling

boolean hostSet = config.getOptionalValue("quarkus.proxy.\"x\".host", String.class).isPresent();
boolean orphan = config.getOptionalValue("quarkus.proxy.\"x\".port", Integer.class).isPresent()
    || config.getOptionalValue("quarkus.proxy.\"x\".non-proxy-hosts", String.class).isPresent();
if (!hostSet && orphan) {
    throw new IllegalArgumentException("quarkus.proxy.\"x\".host missing but sibling keys are set");
}

Try / catch

try {
    application.start();
} catch (IllegalStateException e) {
    if (e.getMessage() != null && e.getMessage().contains(".host is not set")) {
        throw new IllegalStateException("Set the proxy host or remove the orphaned sibling properties", e);
    }
    throw e;
}

Prevention

Always keep host and sibling keys together in config blocks
Check env-var configs (CI containers) for missing host vars
Beware typos like hosts= vs host=
Validate proxy blocks in a startup smoke test

When it happens

Trigger: Setting e.g. quarkus.proxy."x".port=8080 or quarkus.proxy."x".non-proxy-hosts=... without setting quarkus.proxy."x".host, for the default or any named proxy config.

Common situations: Removing/commenting the host line while leaving the rest of the block; typos like hosts= instead of host=; leftover properties from a renamed proxy block.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/3b7b7ba46c1d0a37. Report an issue: GitHub.