flowable/flowable-engine · error · FlowableIllegalArgumentException

Invalid value for enum form property: + value

Error message

Invalid value for enum form property: + value

What it means

EnumFormType.validateValue checks a submitted or stored enum form value against the configured 'values' map (the <flowable:value> entries in the BPMN). If the value is not among them, FlowableIllegalArgumentException 'Invalid value for enum form property: <value>' is thrown. It enforces that only declared enum options are accepted.

Solutions

1. Submit one of the exact values declared via flowable:value entries in the BPMN form property.
2. Align client-side dropdown options with the current BPMN values after a redeploy.
3. Check case-sensitivity and trim whitespace on the submitted value.
4. If dynamic options are needed, replace the enum form type with a custom FormType or store options as variables instead of form metadata.

Example fix

// before
properties.put("priority", "urgent"); // BPMN only defines low|medium|high
// after
properties.put("priority", "high"); // must match a flowable:value entry

Map<String,String> allowed = formService.getTaskFormData(taskId).getFormProperties().stream()
    .filter(p -> p.getId().equals(enumField))
    .map(FormProperty::getType)
    .filter(EnumFormType.class::isInstance)
    .map(p -> ((EnumFormType) p).getValues().keySet())
    .findFirst().orElse(Set.of());
if (!allowed.contains(submittedValue)) {
    throw new IllegalArgumentException("Allowed enum values: " + allowed);
}

try {
    formService.submitTaskFormData(taskId, properties);
} catch (FlowableIllegalArgumentException e) {
    if (e.getMessage().startsWith("Invalid value for enum form property")) {
        refreshAllowedEnumOptions(); // reload form metadata and retry with mapped value
    } else { throw e; }
}

When it happens

Trigger: FormService.submitTaskFormData/startProcessInstanceByForm with a property value not present in the enum's configured values, or setting the variable to an undocumented String which is then converted.

Common situations: BPMN form values updated (renamed options) while clients/old UI still submit old keys, case-sensitivity mismatches ('High' vs 'high'), values defined in one form property but reused with a different set elsewhere.

Understand the failure class

Background: Invalid enum value errors: "Unknown type", "Invalid scope", "must be one of" — when a string is not on the library's allowed list — this error's family across 23 libraries.

Related errors

• form property '" + id + "' is not writable
• form property '" + id + "' is required
• invalid date value " + propertyValue
• Invalid value for enum form property
• Model value should be a String

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/3608157518ec63e5. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-engine/src/main/java/org/flowable/engine/impl/form/EnumFormType.java:67

        validateValue(propertyValue);
        return propertyValue;
    }

    @Override
    public String convertModelValueToFormValue(Object modelValue) {
        if (modelValue != null) {
            if (!(modelValue instanceof String)) {
                throw new FlowableIllegalArgumentException("Model value should be a String");
            }
            validateValue((String) modelValue);
        }
        return (String) modelValue;
    }

    protected void validateValue(String value) {
        if (value != null) {
            if (values != null && !values.containsKey(value)) {
                throw new FlowableIllegalArgumentException("Invalid value for enum form property: " + value);
            }
        }
    }

}

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