Azure Pipelines task version not found or deprecated

What this failure means

An Azure Pipelines job could not start because a pipeline task references a version that has been deprecated, removed, or does not exist in the organization’s task catalog. The pipeline is blocked before any work runs.

Symptoms

Faultline looks for one or more of these log fragments:

Task not found
task.*not found
Task version is not available
version .* is not available
deprecated task
Task '.*' is not recognized
Could not find task
the task is missing

Diagnosis

Azure Pipelines tasks are versioned (e.g., AzureCLI@2, DotNetCoreCLI@3). When a referenced version is unavailable:

• The run fails with Task '[name]' with version '...' not found or Task version is not available.
• Microsoft deprecates old task major versions and eventually removes them.
• A self-hosted agent pool may not have the agent software that ships the required task version.
• A custom or marketplace task may have been removed from the organization’s extension catalog.

Fix steps

1. Update the task to the current major version in azure-pipelines.yml:

   # Before (deprecated)
   - task: AzureCLI@1
   
   # After (current)
   - task: AzureCLI@2
   

2. Check the Azure Pipelines task reference documentation for the current supported version of the task.

3. For marketplace tasks, go to Organization Settings → Extensions and verify the extension is still installed and enabled.

4. For self-hosted agent pools, update the agent to a version that ships the required built-in task.

5. Review Microsoft’s deprecation announcements for the task family — some tasks require migration to a new task name, not just a version bump.

Validation

• The pipeline run starts and the previously failing task step begins execution.
• No Task not found or version is not available message appears.

Why it matters

Azure Pipelines removes deprecated task versions on a rolling schedule. Pipelines that worked for months or years can suddenly fail when a task version they reference is retired without explicit migration. Because the failure happens at pipeline startup, no work runs at all.

Prevention

• Subscribe to Azure DevOps deprecation notices and track pipeline task versions in source control.
• Pin to a task version that has a documented support timeline.
• Review pipelines that use task versions flagged as deprecated in PR validation runs.
• Document which task versions are in use and include a task version review in your quarterly maintenance cycle.

How Faultline detects it

Use faultline explain azure-pipelines-task-not-found to see the full playbook.

faultline analyze build.log
faultline explain azure-pipelines-task-not-found

Generated from playbooks/bundled/log/ci/azure-pipelines-task-not-found.yaml. Do not edit directly.