Azure Pipelines Cross-Stage Output Variable Is Empty

By Daniel Zoghalchali·Latchkey

A value set in one stage reads as empty in a later stage. Cross-stage outputs need three things: the variable set with isOutput=true, an explicit dependsOn, and a stageDependencies.<Stage>.<Job>.outputs[...] reference - miss any one and you get a blank.

What this error means

A downstream stage consumes $[ stageDependencies... ] and the value is empty, so a condition never matches or a deploy uses the wrong target. The producing stage logged the value fine.

# producer logged: ##vso[task.setvariable variable=imageTag;isOutput=true]v42
# consumer condition evaluated against an empty string and skipped

Common causes

Variable not emitted as an output

Only ##vso[task.setvariable variable=x;isOutput=true] variables are visible outside the setting job. Without isOutput=true the value stays job-local.

Wrong reference path or missing dependsOn

Across stages you must use stageDependencies.<Stage>.<Job>.outputs['<stepName>.<var>'], and the consuming stage must dependsOn the producing stage, or the dependency data is not populated.

How to fix it

Emit the variable as an output with a named step

Give the step a name and set the variable with isOutput=true.

jobs:
  - job: build
    steps:
      - bash: echo "##vso[task.setvariable variable=imageTag;isOutput=true]v42"
        name: setTag

Read it via stageDependencies in a dependent stage

Reference the full path and ensure the stage dependsOn the producer.

- stage: Deploy
  dependsOn: Build
  variables:
    imageTag: $[ stageDependencies.Build.build.outputs['setTag.imageTag'] ]
  jobs:
    - job: d
      steps: [ { script: echo $(imageTag) } ]

How to prevent it

• Always name the step that emits an output variable.
• Use dependencies within a stage and stageDependencies across stages.
• Declare an explicit dependsOn whenever you read another stage’s outputs.

Frequently asked questions

Related guides

References

• GitHub Actions documentation