quarkusio/quarkus · error · RuntimeException

principal was null

Error message

principal was null

What it means

Sentinel check in an elytron-undertow integration-test servlet: after authenticated access, req.getUserPrincipal() (or its name) came back null, i.e. the security context did not carry the authenticated principal the test expects. This is a test-app assertion guard, not production code — the input at fault is the servlet request's security context.

Source

Thrown at integration-tests/elytron-undertow/src/main/java/io/quarkus/it/undertow/elytron/GreetingServlet.java:16

package io.quarkus.it.undertow.elytron;

import java.io.IOException;

import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

@WebServlet(name = "ServletGreeting", urlPatterns = "/*")
public class GreetingServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        if (req.getUserPrincipal().getName() == null) {
            throw new RuntimeException("principal was null");
        }
        resp.setStatus(200);
        resp.addHeader("Content-Type", "text/plain");
        resp.getWriter().write("hello");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        if (req.getUserPrincipal().getName() == null) {
            throw new RuntimeException("principal was null");
        }
        String name = req.getReader().readLine();
        resp.setStatus(200);
        resp.addHeader("Content-Type", "text/plain");
        resp.getWriter().write("hello " + name);
    }
}

View on GitHub (pinned to e1c734241f)

Solutions

1. Authenticate the request before invoking the endpoint
2. Verify the elytron/undertow security configuration secures the servlet url-pattern

When it happens

Trigger: Thrown at integration-tests/elytron-undertow/src/main/java/io/quarkus/it/undertow/elytron/GreetingServlet.java:16 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/c868e43aaf4112d0. Report an issue: GitHub.