AWS SAM Direct Invoke - Invalid JSON in payload file

I am trying to invoke a Lambda function locally using the AWS SAM tools in VS Code.

I have this debug configuration in my launch.json file:

{
    "configurations": [
        {
            "type": "aws-sam",
            "request": "direct-invoke",
            "name": "SendEmail",
            "invokeTarget": {
                "target": "template",
                "templatePath": "${workspaceFolder}/LambdaExampleProject/sam-template.yml",
                "logicalId": "SendEmail"
            },
            "lambda": {
                "runtime": "dotnet5.0",
                "environmentVariables": {},
                "payload": {
                    "path": "${workspaceFolder}/LambdaExampleProject/sample-payloads/SendEmailSQSPayload.json"
                }
            }
        }
    ]
}

And this is the contents of the payload file SendEmailSQSPayload.json:

{
    "Records": [
        {
            "messageId": "059f36b4-87a3-44ab-83d2-661975830a7d",
            "receiptHandle": "AQEBwJnKyrHigUMZj6rYigCgxlaS3SLy0a...",
            "body": "Test message.",
            "attributes": {
                "ApproximateReceiveCount": "1",
                "SentTimestamp": "1545082649183",
                "SenderId": "AIDAIENQZJOLO23YVJ4VO",
                "ApproximateFirstReceiveTimestamp": "1545082649185"
            },
            "messageAttributes": {},
            "md5OfBody": "e4e68fb7bd0e697a0ae8f1bb342846b3",
            "eventSource": "aws:sqs",
            "eventSourceARN": "arn:aws:sqs:us-east-2:123456789012:my-queue",
            "awsRegion": "ap-southeast-2"
        }
    ]
}

It is indeed valid JSON in the payload file but VS Code still throws this error:

Invalid JSON in payload file

Am I doing something wrong here? It seems like something that should be super simple according to the documentation.

Thanks in advance for any advice

• OS: Windows 10 x64
• VS Code version: 1.66.2
• AWS Toolkit extension version: 1.37.0

[mr-davidc]

Thanks so much @JadenSimon . That was exactly the problem. The JSON file had UTF-8 with BOM encoding!

After saving the file as plain UTF-8, it now reads the file in fine and all works great. Both absolute files path and relative file paths work including the reference of ${workspaceFolder} (as in my original post).

Thanks again.

[JadenSimon]

Glad to hear! We’re looking into adding better detection for this as BOM problems are not too uncommon. And they’re very frustrating to debug.