Azure Pipelines UseDotNet/UsePythonVersion "version spec did not match"

A tool-installer task could not satisfy the version you asked for. UsePythonVersion only selects versions already on the image, and UseDotNet may fail to download a spec that does not exist or is unreachable.

What this error means

A UsePythonVersion or UseDotNet step fails with Version spec X for architecture Y did not match any version or is not installed on this agent.

##[error]Version spec 3.13 for architecture x64 did not match any version in
Agent.ToolsDirectory.
##[error]Python version 3.13 not found.

Common causes

The version is not preinstalled on the image

UsePythonVersion picks from versions already in the tool cache; a version not on the hosted image is not found.

A wrong or unavailable version spec

A typo, an unreleased version, or a missing architecture variant means no matching runtime can be selected or downloaded.

How to fix it

Request a version the image provides

Pick a version listed for the hosted image, or allow a range so a present minor version matches.

- task: UsePythonVersion@0
  inputs:
    versionSpec: '3.12'
    architecture: 'x64'

Let UseDotNet acquire a valid SDK

For .NET, UseDotNet can download the SDK; confirm the version exists in a release channel before pinning it.

- task: UseDotNet@2
  inputs:
    packageType: 'sdk'
    version: '8.0.x'

How to prevent it

• Check the hosted image software list for available runtime versions.
• Use ranges (3.12, 8.0.x) rather than exact unverified patch versions.
• Confirm the architecture variant exists for the version you pin.

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