quarkusio/quarkus · error · IllegalArgumentException

Segment is null

Error message

Segment is null

What it means

UriBuilder.segment(String...) throws IllegalArgumentException when any element of the segments array is null. The JAX-RS UriBuilder contract requires all path segments to be non-null strings, and RESTEasy Reactive's implementation enforces this eagerly instead of producing a broken URI later.

Source

Thrown at independent-projects/resteasy-reactive/common/runtime/src/main/java/org/jboss/resteasy/reactive/common/jaxrs/UriBuilderImpl.java:1051

    public String getPath() {
        return path;
    }

    public String getQuery() {
        return query;
    }

    public String getFragment() {
        return fragment;
    }

    public UriBuilder segment(String... segments) throws IllegalArgumentException {
        if (segments == null)
            throw new IllegalArgumentException("Segment parameter is null");
        for (String segment : segments) {
            if (segment == null)
                throw new IllegalArgumentException("Segment is null");
            path(Encode.encodePathSegment(segment));
        }
        return this;
    }

    public URI buildFromEncoded(Object... values) throws IllegalArgumentException, UriBuilderException {
        if (values == null)
            throw new IllegalArgumentException("Values is null");
        return buildFromValues(false, true, values);
    }

    public UriBuilder replacePath(String path) {
        if (path == null) {
            this.path = null;
            return this;
        }
        this.path = Encode.encodePath(path);
        return this;

View on GitHub (pinned to e1c734241f)

Solutions

1. Filter or substitute null segments before calling segment(), e.g. stream.filter(Objects::nonNull).toArray(String[]::new)
2. Provide a default value for optional parts (e.g. Objects.requireNonNullElse(part, "default"))
3. Validate inputs at the boundary of your code and fail with a meaningful message before building the URI
4. If the segment may be absent, skip the call entirely or use a builder branch that omits it

Example fix

// before
URI uri = UriBuilder.fromUri(base).segment("api", version, "users").build(); // version == null -> IllegalArgumentException
// after
URI uri = UriBuilder.fromUri(base)
    .segment("api", Objects.requireNonNullElse(version, "v1"), "users")
    .build();

if (segments == null || Arrays.stream(segments).anyMatch(Objects::isNull)) {
    throw new IllegalArgumentException("segments must not contain nulls");
}
uriBuilder.segment(segments);

boolean hasNoNulls(String[] arr) {
    return arr != null && Arrays.stream(arr).allMatch(Objects::nonNull);
}

try {
    uriBuilder.segment(segments);
} catch (IllegalArgumentException e) {
    throw new IllegalArgumentException("Invalid URI segment (null element in " + Arrays.toString(segments) + ")", e);
}

When it happens

Trigger: Calling UriBuilderImpl.segment(...) with a String[] that contains a null element, e.g. uriBuilder.segment("a", null, "b") or passing an array whose entries were not initialized. (Passing a null array raises 'Segment parameter is null' instead.)

Common situations: Building URIs from user input, request parameters, config values, or database fields where one part is null; assembling path parts from optional variables or a List.toArray() of a list containing nulls.

Related errors

• Values is null
• URI was null
• URI is null
• Scheme was null
• path is null

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/082a4165d157ba0d. Report an issue: GitHub.