Azure Pipelines "task X not found" / "could not find task"

By Kaveh Alemi·Latchkey

The pipeline references a task the agent cannot resolve. Either the task name or version is wrong, or it belongs to a Marketplace extension that is not installed in your organization.

What this error means

The run fails before the step executes with a message that the task cannot be found, often naming the task and the version you requested. Built-in tasks fail on a bad version; third-party tasks fail when the extension is absent.

##[error]Job failed: Step input task references task 'UsePythonVersion'
at version '99.x.x' which could not be found.

Common causes

Wrong task name or major version

Tasks are referenced as Name@MajorVersion (e.g. UsePythonVersion@0). A typo or a major version that does not exist makes the task unresolvable.

Marketplace extension not installed

Tasks from a Marketplace extension only exist once an org admin installs that extension. Without it, the agent has no definition for the task.

How to fix it

Use the correct task name and major version

Reference the task as Name@Major with a version that exists.

steps:
  - task: UsePythonVersion@0
    inputs:
      versionSpec: '3.11'

Install the Marketplace extension

1. Open the task’s Marketplace listing and click "Get it free" for your organization.
2. An Azure DevOps org admin must approve the install.
3. Re-run the pipeline once the extension is installed org-wide.

How to prevent it

• Pin tasks to a supported major version you know is installed.
• Document required Marketplace extensions in the repo README.
• Use the pipeline editor’s task picker to insert valid task references.

Frequently asked questions

Related guides

References

• GitHub Actions documentation