quarkusio/quarkus · error · IllegalArgumentException

param was null

Error message

param was null

What it means

NewCookieHeaderDelegate.fromString parses a Set-Cookie header string into a NewCookie and rejects null input per the JAX-RS HeaderDelegate contract. A null string cannot represent a cookie, so an IllegalArgumentException is thrown before any parsing starts.

Source

Thrown at independent-projects/resteasy-reactive/common/runtime/src/main/java/org/jboss/resteasy/reactive/common/headers/NewCookieHeaderDelegate.java:25

import java.util.Map;

import jakarta.ws.rs.core.NewCookie;
import jakarta.ws.rs.ext.RuntimeDelegate;

import org.jboss.resteasy.reactive.common.util.DateUtil;
import org.jboss.resteasy.reactive.common.util.OrderedParameterParser;

/**
 * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
 * @version $Revision: 1 $
 */
public class NewCookieHeaderDelegate implements RuntimeDelegate.HeaderDelegate {
    public static final NewCookieHeaderDelegate INSTANCE = new NewCookieHeaderDelegate();
    private static final String OLD_COOKIE_PATTERN = "EEE, dd-MMM-yyyy HH:mm:ss z";

    public Object fromString(String newCookie) throws IllegalArgumentException {
        if (newCookie == null)
            throw new IllegalArgumentException("param was null");
        String cookieName = null;
        String cookieValue = null;
        String comment = null;
        String domain = null;
        int maxAge = NewCookie.DEFAULT_MAX_AGE;
        String path = null;
        boolean secure = false;
        int version = NewCookie.DEFAULT_VERSION;
        boolean httpOnly = false;
        NewCookie.SameSite sameSite = null;
        Date expiry = null;

        OrderedParameterParser parser = new OrderedParameterParser();
        Map<String, String> map = parser.parse(newCookie, ';');

        for (Map.Entry<String, String> entry : map.entrySet()) {
            String name = entry.getKey();
            String value = entry.getValue();

View on GitHub (pinned to e1c734241f)

Solutions

1. Null-check the cookie string before parsing and treat null as 'no cookie'.
2. Use a MultiValueMap/headers API that returns an empty list, and branch on isEmpty before conversion.
3. Catch IllegalArgumentException when the cookie string is genuinely optional.

Example fix

// before
NewCookie c = (NewCookie) NewCookieHeaderDelegate.INSTANCE.fromString(header);
// after
NewCookie c = header == null ? null : (NewCookie) NewCookieHeaderDelegate.INSTANCE.fromString(header);

if (cookieHeader == null || cookieHeader.isEmpty()) {
    return null; // no cookie present
}

static boolean hasCookie(String setCookieHeader) {
    return setCookieHeader != null && !setCookieHeader.isBlank();
}

try {
    return (NewCookie) NewCookieHeaderDelegate.INSTANCE.fromString(raw);
} catch (IllegalArgumentException e) {
    return null; // null or unparseable cookie
}

When it happens

Trigger: Calling NewCookieHeaderDelegate.fromString(null) directly, or feeding a null header value (e.g. missing Set-Cookie from a response map lookup) into RuntimeDelegate cookie conversion.

Common situations: Proxying/forwarding cookies where the upstream response had no Set-Cookie header; reading cookies from a Map.get that returned null; optional config values for default cookies.

Related errors

• Param was null
• Media type was null
• Param was null
• Does not support fromString
• control character in cookie value

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/fc143102aba02235. Report an issue: GitHub.