flowable/flowable-engine · error · UnsupportedOperationException

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

Error message

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

What it means

ProcessVariableMap.values() throws UnsupportedOperationException unconditionally, and entrySet() below it does the same. The CDI map is intentionally only a keyed get/put facade over BusinessProcess; no enumeration of values or entries is possible.

Solutions

Log or compare specific variables via get(name) instead of dumping the map.
Enumerate variables via the engine's variable query/VariableScope API when you need all entries.
Keep ProcessVariableMap out of toString/logging-generic helpers.

Example fix

// before
logger.debug("Process variables: {}", processVariableMap); // calls entrySet() -> throws

// after
logger.debug("myVar={}, otherVar={}", processVariableMap.get("myVar"), processVariableMap.get("otherVar"));

Defensive patterns

Strategy: try-catch

Try / catch

try { logger.debug("vars={}", processVariableMap); } catch (UnsupportedOperationException e) { /* log named variables via get(name) instead */ }

Prevention

Never log or toString() the CDI variable map (entrySet() throws)
Log only the variables you know by name
Use engine variable queries when a full snapshot is needed

When it happens

Trigger: Calling values() or entrySet() directly; printing the map (Map.toString() calls entrySet()); iterating entries in a for-each; libraries that snapshot a Map's entries.

Common situations: Debug logging like log.debug("vars={}", map) which triggers entrySet/toString; copying all variables; test assertions comparing full maps.

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/4bfa847538949a08. Report an issue: GitHub.

Appendix: source

Thrown at modules/flowable-cdi/src/main/java/org/flowable/cdi/impl/ProcessVariableMap.java:97

    @Override
    public Object remove(Object key) {
        throw new UnsupportedOperationException("ProcessVariableMap.remove is unsupported. Use ProcessVariableMap.put(key, null)");
    }

    @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.");
    }

}

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