AWS SAM YAML template - Unknown Tag !Ref

When I try to deploy my AWS SAM YAML file, it fails saying the !Ref is an unknown tag.

Any ideas to get around this?

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Resources:
  MySimpleFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: index.handler
      Runtime: nodejs4.3
      CodeUri: s3://<bucket>/MyCode.zip
      Events:
        MyUploadEvent:
          Type: S3
          Properties:
            Id: !Ref Bucket
            Events: Create
  Bucket:
    Type: AWS::S3::Bucket

You can add custom YAML tags in your settings.json:

"yaml.customTags": [
  "!Equals sequence",
  "!FindInMap sequence",
  "!GetAtt",
  "!GetAZs",
  "!ImportValue",
  "!Join sequence",
  "!Ref",
  "!Select sequence",
  "!Split sequence",
  "!Sub"
]

First validate your extensions, I eliminated the extension called Redhat yaml and problems solved, I have the next extensions and everything is ok.

• vscode-cfn-lint
• Serverless IDE
• aws-cloudformation-yaml
• AWS Toolkit for Visual Studio Code

The CloudFormation Visual Studio Code extension should manage these tags for you

This error message is almost certainly a false-positive from the YAML parser your IDE is using. To assess the correctness of the AWS SAM template, you should use cfn-python-lint instead, which comes with plugins for most major IDEs (unfortunately not for Visual Studio, but for Visual Studio Code).

The Ansible extension for Visual Studio Code was causing this error message for me. I removed it, and that solved the problem for my situation.

In vscode, click file > save workspace as > click save

Then, open workspace.code-workspace and paste the following:

{   
    "folders": [
      {
        "path": ".."
      }   
    ],   
    "settings": {
      "yaml.customTags": [
        "!Equals sequence",
        "!FindInMap sequence",
        "!GetAtt",
        "!GetAZs",
        "!ImportValue",
        "!Join sequence",
        "!Ref",
        "!Select sequence",
        "!Split sequence",
        "!Sub"
      ]   
    } 
}