What is wrong with my SAM Template?

Question

Can somebody guide me on this?. When running `sam validate --lint` I got the many errors

SAM Template:

```
AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31
Description: Two Lambda functions and two buckets to move and read a CSV file

Globals:
  Function:
    Runtime: python3.11
    CodeUri: src/
    Timeout: 60

Parameters:
  OriginStorageParameter:
    Type: String
    Default: 
      Fn::Sub: "${AWS::StackName}-origin"
  DestinationStorageParameter:
    Type: String
    Default: 
      Fn::Sub: "${AWS::StackName}-destination"

Resources:
  OriginStorage:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: 
        Ref: OriginStorageParameter

DestinationStorage:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: 
        Ref: DestinationStorageParameter

ListenerFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: listener.lambda_handler
      FunctionName: s3-listener
      Events:
        S3Event:
          Type: S3
          Properties:
            Bucket: 
              Ref: OriginStorage
            Events: 
              - s3:ObjectCreated:*
            Filter:
              S3Key:
                Rules:
                - Name: suffix
                  Value: ".csv"
      Policies: 
        - S3ReadPolicy:
            BucketName: 
              Ref: OriginStorageParameter

CopierFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: copier.lambda_handler
      FunctionName: s3-copier
      Events:
        S3Event:
          Type: S3
          Properties:
            Bucket: 
              Ref: DestinationStorage
            Events: 
              - s3:ObjectCreated:*
            Filter:
              S3Key:
                Rules:
                - Name: suffix
                  Value: ".csv"
      Policies: 
        - S3ReadPolicy:
            BucketName: 
              Ref: OriginStorageParameter
        - S3WritePolicy:
            BucketName: 
              Ref: DestinationStorage
```

and the output of the command...

![Enter image description here](/media/postImages/original/IM81dDUZm0RT-Wjn7T9apAmw)

Regards

Jona

Steve Kinsman · Accepted Answer

Hi, you can't use intrinsic functions like Fn::Sub in the Parameters section.  As per https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html. "You can use intrinsic functions only in specific parts of a template. Currently, you can use intrinsic functions in resource properties, outputs, metadata attributes, and update policy attributes. You can also use intrinsic functions to conditionally create stack resources.".

What is wrong with my SAM Template?

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