kestra-io/kestra · error · IllegalArgumentException

Both `namespace` and `flowId` must be set when…

Error message

Both `namespace` and `flowId` must be set when `executionId` is set.

What it means

Thrown by PluginUtilsService when executionId is set (non-null) but exactly one of namespace/flowId is set while the other is null. The contract is: when executionId is provided, namespace and flowId must BOTH be provided (to explicitly target a specific execution), or BOTH omitted (defaults to the current execution's namespace/flowId). Setting only one is ambiguous and rejected as an IllegalArgumentException.

Solutions

When executionId is set, provide BOTH namespace and flowId, or neither.
Verify both Pebble expressions resolve to non-null strings.
If targeting the current execution, omit namespace and flowId entirely.

Example fix

# before
task:
  executionId: "{{ executionId }}"
  namespace: "team.prod"
  # flowId missing

# after
task:
  executionId: "{{ executionId }}"
  namespace: "team.prod"
  flowId: "myflow"

Defensive patterns

Strategy: validation

Validate before calling

if (executionId != null && (namespace == null) != (flowId == null)) {
    throw new IllegalArgumentException("Both `namespace` and `flowId` must be set when `executionId` is set.");
}

Type guard

function isExecutionRefValid(o: { executionId?: string; namespace?: string; flowId?: string }): boolean {
  if (o.executionId) return (!o.namespace && !o.flowId) || (!!o.namespace && !!o.flowId);
  return !o.namespace && !o.flowId;
}

Try / catch

try {
    PluginUtilsService.executionInfo(runContext, executionId, namespace, flowId);
} catch (IllegalArgumentException e) {
    log.error("Invalid execution reference: {}", e.getMessage());
}

Prevention

Provide namespace and flowId together, or not at all, when executionId is set.
Assert both Pebble expressions resolve to non-null before submission.

When it happens

Trigger: A task sets executionId and namespace but forgets flowId; executionId and flowId are set but namespace is null; partial rendering leaves one field resolved and the other blank.

Common situations: Operator references a subflow execution but provides an incomplete identifier; a Pebble variable for namespace or flowId renders to empty/null; copy-paste of a partial config.

Related errors

AI-assisted analysis of kestra-io/kestra@823fada927 (2026-08-14). Data as JSON: /api/errors/79e9b2af97806ef9. Report an issue: GitHub.

Appendix: source

Thrown at core/src/main/java/io/kestra/core/models/tasks/runners/PluginUtilsService.java:168

     */
    @SuppressWarnings("unchecked")
    public static ExecutionInfo executionFromTaskParameters(RunContext runContext, String namespace, String flowId, String executionId) throws IllegalVariableEvaluationException {
        var flowInfo = runContext.flowInfo();

        String realTenantId = flowInfo.tenantId();
        String realExecutionId;
        String realNamespace;
        String realFlowId;
        if (executionId != null) {
            realExecutionId = runContext.render(executionId);

            if (namespace != null && flowId != null) {
                realNamespace = runContext.render(namespace);
                realFlowId = runContext.render(flowId);
                // validate that the flow exists: a.k.a access is authorized by this namespace
                runContext.acl().allowNamespace(realNamespace).check();
            } else if (namespace != null || flowId != null) {
                throw new IllegalArgumentException("Both `namespace` and `flowId` must be set when `executionId` is set.");
            } else {
                realNamespace = flowInfo.namespace();
                realFlowId = flowInfo.id();
            }

        } else {
            if (namespace != null || flowId != null) {
                throw new IllegalArgumentException("`namespace` and `flowId` should only be set when `executionId` is set.");
            }
            realExecutionId = (String) new HashMap<>((Map<String, Object>) runContext.getVariables().get("execution")).get("id");
            realNamespace = flowInfo.namespace();
            realFlowId = flowInfo.id();
        }

        return new ExecutionInfo(realTenantId, realNamespace, realFlowId, realExecutionId);
    }

    /**

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