quarkusio/quarkus · error · RuntimeException

invalid config

Error message

invalid config  ${line}

What it means

When JBang dev mode launches, getConfigurationProperties() reads application properties embedded in a Java source file. Lines starting with the marker //Q:CONFIG must be of the form 'key=value'; if no '=' is found after the marker, the launcher treats the line as invalid configuration and throws. This guards against typos in inline JBang configuration directives.

Solutions

1. Open the JBang script and find the offending line (it is included in the message) and add the missing '=' and value, e.g. //Q:CONFIG quarkus.package.type=uber-jar
2. If the line was meant as a comment, remove or change the //Q:CONFIG prefix so it is not parsed as config
3. Run the app via a regular application.properties instead of inline //Q:CONFIG directives to avoid parser fragility

Example fix

// before
//Q:CONFIG quarkus.package.type
// after
//Q:CONFIG quarkus.package.type=uber-jar

List<String> lines = Files.readAllLines(source);
for (String line : lines) {
    if (line.startsWith("//Q:CONFIG")) {
        String conf = line.substring(10).trim();
        if (!conf.contains("=")) {
            throw new IllegalStateException("Malformed JBang config line (missing '='): " + line);
        }
    }
}

try {
    Properties props = launcher.configurationProperties();
} catch (RuntimeException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("invalid config")) {
        // surface the offending line to the user, then abort or fall back to application.properties
    }
}

When it happens

Trigger: A line in a JBang script starts with //Q:CONFIG but contains no '=' character, e.g. '//Q:CONFIG quarkus.datasource.db-kind' without the value part. Thrown from getConfigurationProperties, called by configurationProperties during JBang dev mode startup.

Common situations: Hand-editing //Q:CONFIG lines in a JBang single-file Quarkus app and deleting the value or the equals sign; copy/paste dropping the '=...' portion; writing a comment-like directive that accidentally starts with //Q:CONFIG but is not real config.

Related errors

• invalid config
• Live reload URL set but no password, remote dev requires a…
• Alias ' ' not found in key store (certificate not found)
• Alias ' ' not found in key store (private key not found)
• Alias ' ' not found in trust store (certificate not found)

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/198e0fbc189d2568. Report an issue: GitHub.

Appendix: source

Thrown at independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/jbang/JBangDevModeLauncherImpl.java:190

            byte[] buf = new byte[10];
            int r;
            while ((r = in.read(buf)) > 0) {
                out.write(buf, 0, r);
            }
            return new String(out.toByteArray(), StandardCharsets.UTF_8);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private static Properties getConfigurationProperties(final Path source) throws IOException {
        Properties properties = new Properties();
        for (String line : Files.readAllLines(source)) {
            if (line.startsWith("//Q:CONFIG")) {
                String conf = line.substring(10).trim();
                int equals = conf.indexOf("=");
                if (equals == -1) {
                    throw new RuntimeException("invalid config  " + line);
                }
                properties.setProperty(conf.substring(0, equals), conf.substring(equals + 1));
            }
        }
        return properties;
    }
}

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