steps template with memoize and outputs has outputs null in cache

[ddlenz]

Pre-requisites

• I have double-checked my configuration
• I have tested with the :latest image tag (i.e. quay.io/argoproj/workflow-controller:latest) and can confirm the issue still exists on :latest. If not, I have explained why, in detail, in my description below.
• I have searched existing issues and could not find a match for this bug
• I'd like to contribute the fix myself (see contributing guide)

What happened? What did you expect to happen?

argo submit memo.yaml
wait for workflow to complete
kubectl get configmap cache-this-cm-doesnt-exist -o yaml

Observed: outputs is null

---
data:
  hello-10: '{"nodeID":"memo-steps-kflv9-3685641709","outputs":null,"creationTimestamp":"2026-05-14T00:54:55Z","lastHitTimestamp":"2026-05-14T00:54:55Z"}'
kind: ConfigMap
---

Expected: outputs is populated

---
data:
  hello-10: '{"nodeID":"memo-steps-kflv9-3685641709","outputs":{"parameters":[{"name":"message","value":"hello"}],"creationTimestamp":"2026-05-14T00:54:55Z","lastHitTimestamp":"2026-05-14T00:54:55Z"}'
kind: ConfigMap
---

Version(s)

v4.0.5

Paste a minimal workflow that reproduces the issue. We must be able to run the workflow; don't enter a workflow that uses private images.

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: memo-steps-
  annotations:
    workflows.argoproj.io/description: Test memoization
spec:
  entrypoint: main
  templates:
    - name: main
      steps:
        - - name: echo-and-wait-step
            template: echo-and-wait
            arguments:
              parameters:
                - name: time
                  value: 10
                - name: message
                  value: "hello"
      memoize:
        key: "hello-10"
        cache:
          configMap:
            name: cache-this-cm-doesnt-exist
      outputs:
        parameters:
          - name: message
            valueFrom:
              parameter: "{{ steps.echo-and-wait-step.outputs.parameters.message }}"

    - name: echo-and-wait
      inputs:
        parameters:
          - name: message
          - name: time
      script:
        image: alpine:3.17.2
        command: [sh]
        source: |
          set -e
          date
          echo {{inputs.parameters.message}} > /tmp/msg
          sleep {{inputs.parameters.time}}
      outputs:
        parameters:
          - name: message
            valueFrom:
              path: /tmp/msg

Logs from the workflow controller

kubectl logs -n argo deploy/workflow-controller | grep ${workflow}

Logs from in your workflow's wait container

kubectl logs -n argo -c wait -l workflows.argoproj.io/workflow=${workflow},workflow.argoproj.io/phase!=Succeeded