Output from a Skipped Step Used as a Parameter Causes error=requeue and Workflow hangs

[ArmineAzizyan]

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?

In a steps: workflow, referencing the output parameter of a step that may be skipped causes the workflow to hang or repeatedly requeue. This occurs when the skipped step’s output is used inside another step’s arguments: or when: clause

This behavior matches a reported issue for DAG workflows, but issue remains reproducible for steps

Version(s)

v4.0.4

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.

piVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: skipped-stage-example-steps-
spec:
  entrypoint: main
  arguments:
    parameters:
      - name: run-stage-b
        value: "false"

  templates:

  - name: main
    inputs:
      parameters:
        - name: run-stage-b
    steps:

      # Step A always runs
      - - name: stage-a
          template: stage-a

      # Step B runs only when run-stage-b == "true"
      - - name: stage-b
          template: stage-b
          when: "{{= inputs.parameters['run-stage-b'] == 'true' }}"

      # NEW: Stage C runs only if stage-b ran AND output == "hello from stage B"
      - - name: stage-c
          template: stage-c
          when: "{{= steps['stage-b'].outputs.parameters['output-message'] == 'hello from stage B' }}"

      # Stage D always runs, even if stage-b was skipped
      - - name: stage-d
          template: stage-d
          arguments:
            parameters:
              - name: message-from-a
                value: "{{steps.stage-a.outputs.parameters.output-message}}"
              - name: message-from-b
                value: "{{steps.stage-b.outputs.parameters.output-message}}"

  # -------------------------
  # STAGE A
  # -------------------------
  - name: stage-a
    outputs:
      parameters:
        - name: output-message
          valueFrom:
            path: /tmp/output.txt
    container:
      image: alpine:3.18
      command: [sh, -c]
      args: ["echo 'hello from stage A' | tee /tmp/output.txt"]

  # -------------------------
  # STAGE B (optional)
  # -------------------------
  - name: stage-b
    outputs:
      parameters:
        - name: output-message
          valueFrom:
            path: /tmp/output.txt
    container:
      image: alpine:3.18
      command: [sh, -c]
      args: ["echo 'hello from stage B' | tee /tmp/output.txt"]

  # -------------------------
  # STAGE C (conditional)
  # -------------------------
  - name: stage-c
    container:
      image: alpine:3.18
      command: [sh, -c]
      args:
        - |
          echo "stage-c ran because stage-b output matched the expected value"

  # -------------------------
  # STAGE D (always runs)
  # -------------------------
  - name: stage-d
    inputs:
      parameters:
        - name: message-from-a
        - name: message-from-b
    container:
      image: alpine:3.18
      command: [sh, -c]
      args:
        - |
          echo "stage-d received: [{{inputs.parameters.message-from-a}}] and [{{inputs.parameters.message-from-b}}]"

Logs from the workflow controller

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

workflow-controller-5c69d51257-pbaxv time=2026-04-16T18:11:30.029Z level=ERROR msg="Failed to resolve references" error=requeue component=workflow_worker workflow=skipped-stage-example-steps-wxp9j namespace=argo stepName=stage-c                                                                                                                                                                                      

workflow-controller-5c69d51257-pbaxv time=2026-04-16T18:11:31.034Z level=ERROR msg="Failed to resolve references" component=workflow_worker workflow=skipped-stage-example-steps-wxp9j namespace=argo stepName=stage-c error=requeue                                                                                                                                                                                               

workflow-controller-5c69d51257-pbaxv time=2026-04-16T18:11:32.042Z level=ERROR msg="Failed to resolve references" workflow=skipped-stage-example-steps-wxp9j stepName=stage-c error=requeue namespace=argo component=workflow_worker                                                                                                                                                                                               

workflow-controller-5c69d51257-pbaxv time=2026-04-16T18:11:33.049Z level=ERROR msg="Failed to resolve references" workflow=skipped-stage-example-steps-wxp9j error=requeue namespace=argo stepName=stage-c component=workflow_worker

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

[coderabbitai]

⚠️ Possible Duplicate Issue(s)

• Workflow hangs when 'when' clause references skipped step outputs #15873

🔗 Related PRs

#15442 - fix: requeue workflow if expected variables are missing. Fixes #15513 [merged]
#15736 - fix: add stepgroup and taskgroup to scope. Fixes #15737 [merged]

---

📝 Issue Planner

_{Check the box below or use the @coderabbitai plan command to generate an implementation plan and prompts that you can use with your favorite coding assistant.}

• Create Plan

---

🧪 Issue enrichment is currently in open beta.

You can configure auto-planning by selecting labels in the issue_enrichment configuration.

To disable automatic issue enrichment, add the following to your .coderabbit.yaml:

issue_enrichment:
  auto_enrich:
    enabled: false

💬 Have feedback or questions? Drop into our discord!

[garireo2549]

I'm experiencing this issue in my environment as well. (v.4.0.4)

[KowalczykBartek]

hi @ArmineAzizyan - I verified your example works with my fix #15932 , I hope it will be merged soon (my original issue #15873)

[ArmineAzizyan]

hi @ArmineAzizyan - I verified your example works with my fix #15932 , I hope it will be merged soon (my original issue #15873)

@KowalczykBartek thanks for checking that! Good to know the fix works

[sfrique]

We are hitting this as well, we just had a major upgrade to v4

[peoe]

Same here.