flowable/flowable-engine · error · UnsupportedOperationException

org.flowable.cdi.impl.ProcessVariableMap.entrySet() is not…

Error message

org.flowable.cdi.impl.ProcessVariableMap.entrySet() is not supported.

What it means

ProcessVariableMap is a read-only, map-like view over CDI-resolved process variables in Flowable's CDI integration. It deliberately does not support bulk views such as values() or entrySet(), because process variables live in the engine, not in an in-memory map. Calling entrySet() immediately throws UnsupportedOperationException with this message.

Solutions

Do not iterate the map directly; look up individual variables with get(name) instead.
Use the Flowable API to enumerate variables: runtimeService.getVariables(executionId) or taskService.getVariables(taskId), which return a real Map.
If you need a snapshot map, fetch variables via the engine services and copy that result, not the CDI ProcessVariableMap.

Example fix

// before
for (Map.Entry<String, Object> e : processVariables.entrySet()) { ... }
// after
Map<String, Object> vars = runtimeService.getVariables(executionId);
for (Map.Entry<String, Object> e : vars.entrySet()) { ... }

Defensive patterns

Strategy: type-guard

Validate before calling

if (map instanceof ProcessVariableMap) { /* entrySet unsupported */ }

Type guard

boolean isIterable(Map<String,Object> m) { return !(m instanceof org.flowable.cdi.impl.ProcessVariableMap); }

Try / catch

try { map.entrySet().iterator(); } catch (UnsupportedOperationException e) { /* fall back to engine variable query */ }

Prevention

Never iterate CDI process-variable maps directly; fetch via RuntimeService/TaskService for enumeration
When writing generic Map-consuming code, exclude engine-backed map views

When it happens

Trigger: Calling entrySet() (or values(), keySet()-style iteration) on a ProcessVariableMap instance obtained via CDI injection of @ProcessVariable Map<String,Object> or BusinessProcess.getProcessVariables()-style map access.

Common situations: Developers treat the injected process-variable map like a normal HashMap and try to iterate entries, stream over entrySet(), or copy it with new HashMap<>(processVariableMap), or log it via toString-based debugging that touches entrySet.

Understand the failure class

Background: UnsupportedOperationException and "is not supported" errors: when a library deliberately refuses a call — this error's family across 30 libraries.

Related errors

AI-assisted analysis of flowable/flowable-engine@d6d39ce1c6 (2026-09-11). Data as JSON: /api/errors/7aa75e1ffba2cd08. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-cdi/src/main/java/org/flowable/cdi/impl/ProcessVariableMap.java:102

    @Override
    public void clear() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".clear() is not supported.");
    }

    @Override
    public Set<String> keySet() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".keySet() is not supported.");
    }

    @Override
    public Collection<Object> values() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".values() is not supported.");
    }

    @Override
    public Set<Map.Entry<String, Object>> entrySet() {
        throw new UnsupportedOperationException(ProcessVariableMap.class.getName() + ".entrySet() is not supported.");
    }

}

View on GitHub (pinned to d6d39ce1c6)