Amazon web services – AWS Lambda S3 Event Trigger – Object Key Has Pluses Instead of Spaces

I have an AWS Lambda function set up as an event source for an S3 bucket to process newly uploaded PDF files. However, I’ve noticed that when a file with spaces in its name is uploaded, the event data I receive in the Lambda function has pluses (+) instead of spaces in the key property of the S3 event object.

For example, if I upload a file named "World War.pdf" to my S3 bucket, the Lambda event object shows the key as "public/World+War.pdf":

{
    "s3SchemaVersion": "1.0",
    "configurationId": "arn:aws:cloudformation:eu-west-1:12345673333312:stack/my-lambda-stack/...",
    "bucket": {
        "name": "mybucket",
        "ownerIdentity": { "principalId": "EXAMPLE" },
        "arn": "arn:aws:s3:::mybucket"
    },
    "object": {
        "key": "public/World+War.pdf",
        "size": 40656,
        "eTag": "123456789abcdef",
        "sequencer": "1234567890ABCDEF"
    }
}

This causes issues when I try to use this key to access the file in my S3 bucket, as the actual file name contains spaces and not pluses.

What I’ve tried:

1. I have considered using decodeURIComponent to convert the + back to spaces, but I’m unsure if this is a reliable solution, or if I’m supposed to handle these keys differently.

   const key = decodeURIComponent(event.Records[0].s3.object.key);

2. I have also looked into the S3 event notification configurations to see if there’s a way to receive the key without URL encoding, but found nothing in the AWS documentation.

Questions:

1. Why does AWS encode the S3 object key in the event, and is decodeURIComponent the recommended approach to decode it?
2. Is there a configuration in AWS S3 or Lambda that I can set to receive the object key with spaces instead of pluses?

CloudWatch Error Message:

Error processing and ingesting PDF: public/World+War.pdf. Error: NoSuchKey: The specified key does not exist.

Any help or guidance on this would be greatly appreciated!