quarkusio/quarkus · error · IllegalArgumentException

Cookie value was null

Error message

Cookie value was null

What it means

CookieParser.parseCookies throws IllegalArgumentException when the Cookie header string passed in is null. It is a strict precondition check: parsing cannot proceed without a header value. Callers are expected to treat a missing Cookie header as 'no cookies' rather than passing null.

Source

Thrown at independent-projects/resteasy-reactive/common/runtime/src/main/java/org/jboss/resteasy/reactive/common/util/CookieParser.java:11

package org.jboss.resteasy.reactive.common.util;

import java.util.ArrayList;
import java.util.List;

import jakarta.ws.rs.core.Cookie;

public class CookieParser {
    public static List<Cookie> parseCookies(String cookieHeader) {
        if (cookieHeader == null) {
            throw new IllegalArgumentException("Cookie value was null");
        }
        // cookie headers can be separated by "," (HTTP header separator), or ";" (Cookie separator)
        // FIXME: the current cookie RFC doesn't mention params for cookies sent by the client
        // doesn't mention $ as a prefix either
        // FIXME: make this faster if we have a single cookie
        try {
            List<Cookie> cookies = new ArrayList<>();

            int version = 0;
            String domain = null;
            String path = null;
            String cookieName = null;
            String cookieValue = null;

            String[] parts = cookieHeader.split("[;,]");
            for (String part : parts) {
                String[] nv = part.split("=", 2);
                String name = nv.length > 0 ? nv[0].trim() : "";

View on GitHub (pinned to e1c734241f)

Solutions

1. Null-check the header value before calling parseCookies and return an empty list instead
2. Use the framework's request.getCookies() (Jakarta REST HttpHeaders) which handles absence gracefully
3. Wrap the call and convert IllegalArgumentException to an empty result if null is expected in your context

Example fix

// before
List<Cookie> cookies = CookieParser.parseCookies(request.getHeader("Cookie"));
// after
String header = request.getHeader("Cookie");
List<Cookie> cookies = header == null ? List.of() : CookieParser.parseCookies(header);

String cookieHeader = request.getHeader("Cookie");
List<Cookie> cookies = cookieHeader == null ? List.of() : CookieParser.parseCookies(cookieHeader);

List<Cookie> safeParseCookies(String header) { return header == null ? List.of() : CookieParser.parseCookies(header); }

List<Cookie> cookies;
try {
    cookies = CookieParser.parseCookies(header);
} catch (IllegalArgumentException e) {
    cookies = List.of(); // no Cookie header sent
}

When it happens

Trigger: Calling CookieParser.parseCookies(null), typically after getHeader("Cookie") returned null on a request with no Cookie header.

Common situations: Server-side header parsing where the incoming request has no cookies; utility code that forwards header values without a null check.

Related errors

• Different array length
• File does not exist: ${file}
• File is not a regular file: ${file}
• File cannot be read: ${file}
• Offset (${offset}) must be >= 0: ${file}

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/19f92ef2f88a65f4. Report an issue: GitHub.