Invalid base64 Error when invoking Lambda - AWS CLI [Fixed]

# Invalid base64 Error when invoking Lambda - AWS CLI

The "Invalid base64: {"key": "value"}" error most often occurs when a Lambda function is invoked with --payload parameter consisting of JSON without setting the --cli-binary-format to raw-in-base64-out.

To solve the error, set the --cli-binary-format parameter to raw-in-base64-out when invoking the Lambda function.

Copied!
aws lambda invoke --function-name testFunction --cli-binary-format raw-in-base64-out --payload '{"name": "John Smith"}' response.json

If you are on Windows, you have to escape the double quotes in the --payload parameter - '{\"name\": \"John Smith\"}'.

The reason the AWS CLI throws the error is that by default the --payload parameter is of type blob and expects valid base64 encoded input - docs.

By setting the --cli-binary-format parameter to raw-in-base64-out we are able to provide a raw JSON string to the --payload parameter.

For example, if we had an event.json file with the following contents.

Copied!
{
  "name": "John Doe"
}

Then you have to invoke the lambda function as follows.

Copied!
aws lambda invoke --function-name testFunction --cli-binary-format raw-in-base64-out --payload file://event.json response.json

If we were to not set the --cli-binary-format parameter we would still get the "Invalid base64" error.

I've also written detailed guides on how to invoke a Lambda function using AWS CLI and how to create a lambda function with AWS CLI.

# Additional Resources

You can learn more about the related topics by checking out the following tutorials:

• Create a Role with AWS CLI - Complete Guide
• View your AWS CLI logs in Real Time (tail)
• How to turn off the Pager in AWS CLI
• Tag an S3 Bucket with AWS CLI
• AWS CDK Tutorial for Beginners - Step-by-Step Guide
• How to use Parameters in AWS CDK
• Cannot find module (AWS Lambda Error) [Solved]
• Download the Code of an AWS Lambda Function
• How to handle Errors in AWS Lambda using Typescript
• AWS Lambda Task timed out error [Solved]