quarkusio/quarkus · error · MessageBundleException

A constant of a localized enum may not contain '_$': {consta

Error message

A constant of a localized enum may not contain '_$': {constant}

What it means

Qute uses '_$' as a special separator when deriving enum-constant message keys, so enum constants containing the literal sequence '_$' would produce ambiguous keys. enumConstantSeparator() throws MessageBundleException if any constant of a localized enum contains '_$'.

Source

Thrown at extensions/qute/deployment/src/main/java/io/quarkus/qute/deployment/MessageBundleProcessor.java:1217

                                }
                            }
                            // Render the template
                            // At this point it's already validated that the method returns String
                            bc.return_(bc.invokeInterface(
                                    io.quarkus.qute.deployment.Descriptors.TEMPLATE_INSTANCE_RENDER, templateInstance));
                        }
                    });
                });
            }
            implementResolve(defaultBundleImpl, cc, keyMap, resolveMethodPrefix, generatedClassName);
        });
        return generatedClassName;
    }

    private String enumConstantSeparator(Set<String> enumConstants) {
        for (String constant : enumConstants) {
            if (constant.contains("_$")) {
                throw new MessageBundleException("A constant of a localized enum may not contain '_$': " + constant);
            }
            if (constant.contains("$") || constant.contains("_")) {
                // If any of the constants contains "_" or "$" then "_$" is used
                return "_$";
            }
        }
        return "_";
    }

    private String toEnumConstantKey(String methodName, String separator, String enumConstant) {
        return methodName + separator + enumConstant;
    }

    private void generateEnumConstantMessageMethod(ClassCreator bundleCreator, String bundleName, String locale,
            ClassInfo bundleInterface, ClassInfo defaultBundleInterface, String enumConstantKey,
            Map<String, MessageMethod> keyMap, String messageTemplate,
            BuildProducer<MessageBundleMethodBuildItem> messageTemplateMethods) {
        String templateId = null;

View on GitHub (pinned to e1c734241f)

Solutions

Rename the enum constant to remove the '_$' sequence
Do not localize that enum via the message bundle mechanism
Split the constant into a name without special characters plus separate data

Example fix

// before
enum Codes { A_$1, A_B }
// after
enum Codes { A_1, A_B }

Defensive patterns

Strategy: validation

Validate before calling

for (Field f : MyEnum.class.getEnumConstants()) {
    if (((Enum<?>) f).name().contains("_$"))
        throw new IllegalStateException("Enum constant contains '_$': " + ((Enum<?>) f).name());
}

Prevention

Coding-standard check banning '_$' in enum constant names
Review generated/mapped enum names before localizing them

When it happens

Trigger: Localizing an enum (via a message bundle method taking the enum) where at least one enum constant name contains the substring "_$" and another constant contains '_' or '$' (triggering '_$' as separator).

Common situations: Machine-generated or encoded enum constant names that embed '_$'; constants like FOO_$BAR colliding with the separator scheme.

Related errors

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/0e210a47880ee95c. Report an issue: GitHub.