quarkusio/quarkus · error · IllegalArgumentException

path is null

Error message

path is null

What it means

UriBuilderImpl.path(String) throws 'path is null' when the segment argument is null. The JAX-RS UriBuilder contract requires IllegalArgumentException for null path arguments. The segment is appended to the internal path list via paths(), which cannot accept null. Passing an empty string is allowed.

Source

Thrown at independent-projects/resteasy-reactive/common/runtime/src/main/java/org/jboss/resteasy/reactive/common/jaxrs/UriBuilderImpl.java:394

            } else {
                if (encode)
                    segment = Encode.encodePath(segment);
                if ("".equals(path)) {
                    path = segment;
                } else if (segment.startsWith("/")) {
                    path += segment;
                } else {
                    path += "/" + segment;
                }
            }

        }
        return path;
    }

    public UriBuilder path(String segment) throws IllegalArgumentException {
        if (segment == null)
            throw new IllegalArgumentException("path is null");
        path = paths(encode, path, segment);
        return this;
    }

    @SuppressWarnings("unchecked")
    public UriBuilder path(Class resource) throws IllegalArgumentException {
        if (resource == null)
            throw new IllegalArgumentException("path is null");
        Path ann = (Path) resource.getAnnotation(Path.class);
        if (ann != null) {
            String[] segments = new String[] { ann.value() };
            path = paths(true, path, segments);
        } else {
            throw new IllegalArgumentException("class must be annotated with @Path");
        }
        return this;
    }

View on GitHub (pinned to e1c734241f)

Solutions

1. Check for null before calling: if (segment != null) builder.path(segment);
2. Default optional path config to an empty string instead of null
3. Fail fast with Objects.requireNonNull(segment, 'segment') at your call site
4. Trace where the null originated (config/lookup) and fix the source

Example fix

// before: builder.path(config.basePath()); // throws if null // after: String p = config.basePath(); builder.path(p != null ? p : "");

if (segment == null) {
    throw new IllegalArgumentException('path segment must not be null');
}

static boolean hasPath(String segment) {
    return segment != null;
}

try {
    builder.path(segment);
} catch (IllegalArgumentException e) {
    throw new IllegalArgumentException('path segment was null; check config/annotation lookup', e);
}

When it happens

Trigger: Calling builder.path(null) or path(variable) where the variable is null - e.g. an optional path config value absent, a map.get() miss, or a lookup that returned null.

Common situations: Reading a path fragment from absent configuration; an earlier null propagating through path concatenation; test code passing null to probe error handling.

Related errors

• URI is null
• Scheme was null
• Illegal URI template${uriTemplate}
• invalid host
• invalid port

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/14c65e7fa3507368. Report an issue: GitHub.