keycloak/keycloak · error · IllegalArgumentException

values parameter is null

Error message

values parameter is null

What it means

Guard at the top of build(Object... values): the varargs array itself is null. Calling build() with NO arguments yields an empty array, not null, so this only triggers when a caller passes an explicit null array - typically build((Object[]) null) or a null Object[] variable. Distinct from a null element inside the array (that is error 171).

Source

Thrown at common/src/main/java/org/keycloak/common/util/KeycloakUriBuilder.java:661

        if (fragment != null) addToPathParamList(params, set, fragment);

        return params;
    }

    private void addToPathParamList(List<String> params, HashSet<String> set, String string) {
        Matcher matcher = PathHelper.URI_PARAM_PATTERN.matcher(PathHelper.replaceEnclosedCurlyBraces(string));
        while (matcher.find()) {
            String param = matcher.group(1);
            if (set.contains(param)) continue;
            else {
                set.add(param);
                params.add(param);
            }
        }
    }

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

    public String buildAsString(Object... values) throws IllegalArgumentException {
        if (values == null) throw new IllegalArgumentException("values parameter is null");
        return buildFromValuesAsString(true, false, values);
    }

    protected URI buildFromValues(boolean encodeSlash, boolean encoded, Object... values) {
        String buf = buildFromValuesAsString(encodeSlash, encoded, values);
        try {
            return new URI(buf);
        } catch (Exception e) {
            throw new RuntimeException("Failed to create URI: " + buf, e);
        }
    }

    protected String buildFromValuesAsString(boolean encodeSlash, boolean encoded, Object... values) {

View on GitHub (pinned to 66c7e15a37)

Solutions

1. Replace a null array with an empty array before calling: build(args == null ? new Object[0] : args).
2. Return an empty array (not null) from the method that produces the args.
3. Call build() with no arguments when you have nothing to pass.

Example fix

// before
Object[] vals = resolveArgs(); // may be null
URI u = builder.build(vals);

// after
Object[] vals = resolveArgs();
URI u = builder.build(vals == null ? new Object[0] : vals);

if (values == null) values = new Object[0];
URI u = builder.build(values);

private static Object[] nonNullArgs(Object[] in) {
    return in == null ? new Object[0] : in;
}

When it happens

Trigger: Object[] args = computeArgs(); builder.build(args); where computeArgs() returned null; or an explicit build((Object[]) null).

Common situations: A helper that resolves an optional argument list and returns null for 'none' instead of an empty array; reflective invocation passing a null args array.

Related errors

• segments parameter was null
• NULL value for template parameter: {param}
• Failed to create URI: {buf}
• A value was null
• name parameter is null

AI-assisted analysis of keycloak/keycloak@66c7e15a37 (2026-08-14). Data as JSON: /api/errors/98afb97649e3784b. Report an issue: GitHub.