1. 在“template.yaml”文件中，检查outputs部分的格式是否正确。outputs部分应该包含至少一个输出值以及它们的名称。示例代码如下：

Outputs:
  HelloWorldApi:
    Description: "API Gateway endpoint URL for Prod environment"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"

2. 检查“sam deploy”命令参数是否正确。应该指定正确的区域、存储桶和堆栈名称。示例代码如下：

sam deploy --template-file .aws-sam/build/template.yaml --stack-name HelloWorld --region us-east-1 --capabilities CAPABILITY_IAM

3. 如果还是出现错误，请从头检查AWS SAM项目的配置和环境设置。可能需要运行“aws configure”命令来设置正确的AWS访问密钥和秘密访问密钥。

最终的“template.yaml”文件：

Transform: 'AWS::Serverless-2016-10-31'
Resources:
  HelloWorldFunction:
    Type: 'AWS::Serverless::Function'
    Properties:
      Handler: app.lambda_handler
      Runtime: python3.6
      CodeUri: .
  HelloWorldApi:
    Type: 'AWS::Serverless::Api'
    Properties:
      StageName: Prod
  HelloWorldApiDeployment:
    Type: 'AWS::Serverless::Deployment'
    Properties:
      Description: "Deployment package for the HelloWorld API"
  HelloWorldPermission:
    Type: 'AWS::Lambda::Permission'
    Properties:
      FunctionName: !GetAtt HelloWorldFunction.Arn
      Action: 'lambda:InvokeFunction'
      Principal: apigateway.amazonaws.com
  HelloWorldMethod:
    Type: 'AWS::ApiGateway::Method'
    Properties:
      AuthorizationType: NONE
      HttpMethod: GET
      Integration: 
        Type: AWS_PROXY
        IntegrationHttpMethod: POST
        Uri: !Sub "arn:aws:apigateway:${AWS::Region}:lambda:path/2015-03-31/functions/${HelloWorldFunction.Arn}/invocations"
      ResourceId: !GetAtt HelloWorldApi.RootResourceId
      RestApiId: !Ref HelloWorldApi
Outputs:
  HelloWorldApi:
    Description: "API Gateway endpoint URL for Prod environment"
    Value: !Sub "https://${ServerlessRestApi}.execute-api.${AWS::Region}.amazonaws.com/Prod/hello/"