Below is the code for azure-pipelines.yml (assume it is indented correctly, I had to copy and paste from VSCode to a text file, as .yml isn't a supported format within this question/answer portal):

azure-pipelines.yml

This pipeline validates an AWS CloudFormation template.

trigger:

• main # Trigger this pipeline whenever changes are pushed to the 'main' branch

pool:

vmImage: 'ubuntu-latest' # Use a Microsoft-hosted Ubuntu agent

steps:

• checkout: self # Checkout the repository where this pipeline file exists
• task: AWSCloudFormationStackParameters@1 # Task to parse CFN parameters (useful later) inputs:

templateFile: 'cloudformation/s3-bucket-template.yaml'

templateInputMode: 'file'

displayName: 'Parse CloudFormation Template Parameters'

• task: AWSCloudFormationDeployStack@1 # This task is also used for validation

inputs:

awsCredentials: 'AWS-CloudFormation-Connection' # Your service connection name

regionName: 'us-east-1' # Or your preferred AWS region (e.g., 'us-west-2')

stackName: 'Validation-Stack-DoNotCreate' # A dummy stack name for validation

templateFile: 'cloudformation/s3-bucket-template.yaml'

deploymentAction: 'VALIDATE_ONLY' # Key setting: only validate, not deploy

displayName: 'Validate CloudFormation Template'

Hi Shaan T

Could you please follow the belos steps:

• Reinstall the extension -> Go to Azure DevOps -> Extensions -> Browse Marketplace -> AWS Tool Kit -> Get it Free -> Select the organization -> Install. After reinstalling, wait a few minutes and restart your browser session.
• Create a new pipeline using the Classic Editor. Try adding the AWSCloudFormationDeployStack task manually. If it doesn’t appear in the task picker, the extension isn’t registering correctly. I have checked from my end, I am able to see only these tasks. there is no AWSCloudFormationDeployStack
• Create a dummy classic pipeline with any AWS task. Save and run it once. This can sometimes force Azure DevOps to register the extension tasks across the organization.
• To test task availability in YAML:

    trigger:
    - none
    pool:
      vmImage: 'windows-latest'
    steps:
    - task: AWSCloudFormationDeployStack@1
      inputs:
        awsCredentials: '<your-service-connection>'
        regionName: 'us-east-1'
        stackName: 'TestStack'
        templateSource: 'file'
        templateFile: 'template.yaml'
  

  If this fails with the same error, it confirms the task isn’t registered.

Additional References:

https://aws.amazon.com/blogs/devops/use-the-aws-toolkit-for-azure-devops-to-automate-your-deployments-to-aws/#:~:text=In%20this%20post%2C%20I%20will%20walk%20you%20through,directly%20from%20your%20existing%20Azure%20DevOps%20build%20pipelines.

Hope this helps!

Please Let me know if you have any queries.