cnf-lint warns "python3.14" is not a valid Lambda Runtime #4367
Description
CloudFormation Lint Version
amazonwebservices.aws-toolkit-vscode:3.95.0
What operating system are you using?
Mac
Describe the bug
I'm developing a CloudFormation template on VSCode with the help of the AWS toolkit extension. An unexpected problem is reported, it seems cnf-lint thinks "python3.14" is not a valid Lambda Runtime.
Here's some example code:
ExampleFunction:
Type: AWS::Lambda::Function
Properties:
FunctionName: !Sub "${AWS::StackName}-example"
Runtime: python3.14
Handler: index.handler
Role: !GetAtt LambdaExecutionRole.Arn
Code:
ZipFile: |
import json
def handler(event, context):
return {
'statusCode': 200,
'body': json.dumps({'message': 'Deploy backend code separately'})
}The following problem is reported by cfn-lint(E3030):
'python3.14' is not one of ['dotnet6', 'dotnet8', 'dotnetcore1.0', 'dotnetcore2.0', 'dotnetcore2.1', 'dotnetcore3.1', 'go1.x', 'java11', 'java17', 'java21', 'java8', 'java8.al2', 'nodejs', 'nodejs10.x', 'nodejs12.x', 'nodejs14.x', 'nodejs16.x', 'nodejs18.x', 'nodejs20.x', 'nodejs22.x', 'nodejs24.x', 'nodejs4.3', 'nodejs4.3-edge', 'nodejs6.10', 'nodejs8.10', 'provided', 'provided.al2', 'provided.al2023', 'python2.7', 'python3.10', 'python3.11', 'python3.12', 'python3.13', 'python3.6', 'python3.7', 'python3.8', 'python3.9', 'ruby2.5', 'ruby2.7', 'ruby3.2', 'ruby3.3', 'ruby3.4']
python3.14 has been available as a Lamda runtime since the end of 2025.
Expected behavior
No error should be raised by cfn-lint.
Reproduction template
ExampleFunction:
Type: AWS::Lambda::Function
Properties:
FunctionName: !Sub "${AWS::StackName}-example"
Runtime: python3.14
Handler: index.handler
Role: !GetAtt LambdaExecutionRole.Arn
Code:
ZipFile: |
import json
def handler(event, context):
return {
'statusCode': 200,
'body': json.dumps({'message': 'Deploy backend code separately'})
}