Issue with deploying aspnetcore 3.1 into aws lambda

[bveeni]

Hi everyone,
Hope everyone is doing well.
I have my aspnetcore 3.1 app, which was working fine before, with deployment in AWS lambda with runtime parameter of dotnetcore3.1.
But recently, I noticed that, it is throwing following error, when I tried to deploy in Lambda.

Resource handler returned message: "The runtime parameter of dotnetcore3.1 is no longer supported for creating or updating AWS Lambda functions. We recommend you use the new runtime (dotnet6) while creating or updating functions. (Service: Lambda, Status Code: 400, Request ID: d38a36f3-16ae-4b0f-8df4-371622b369bb)" (RequestToken: a0823116-7ef3-6839-47d5-99915dbb3ac2, HandlerErrorCode: InvalidRequest

Here is my value for parameter "DefaultFunction" in serverless.template

  "DefaultFunction" : {
      "Type" : "AWS::Serverless::Function",
      "Properties": {
        "Handler": "LambdaTest::LambdaTest.LambdaFunction::FunctionHandlerAsync",
        "Runtime": "dotnetcore3.1",
        "CodeUri": "",
        "Description": "Default function",
        "MemorySize": 10240,
        "Timeout": 900,
        "Role": null,
        "Policies": [ "AWSLambda_FullAccess" ],
        "Events": {
          "ProxyResource": {
            "Type": "Api",
            "Properties": {
              "Path": "/{proxy+}",
              "Method": "ANY",
               "RestApiId": {
                "Ref": "ServerlessRestApi"
              }
            }
          },
            "RootResource": {
            "Type": "Api",
            "Properties": {
              "Path": "/",
              "Method": "ANY",
              "RestApiId": {
                "Ref": "ServerlessRestApi"
              }
            }
          }
        }
      }
    }
  },

I would like to confirm that if dotnet3.1 is no longer supported for AWS Lambda? If so, then what changes should I implement to make it work.
Thank you

[ashovlin]

Lambda support for .NET Core 3.1 entered "Phase 1" of the deprecation policy on April 3rd, 2023.

Lambda no longer applies security patches or other updates to the runtime. You can no longer create functions that use the runtime, but you can continue to update existing functions. This includes updating the runtime, and rolling back to the previous runtime. Note that functions that use a deprecated runtime are no longer eligible for technical support.

Lambda is currently rolling out "Phase 2" since it's been 30 days since phase 1.

Phase 2 - you can no longer create or update functions that use the runtime. To update a function, you need to migrate it to a supported runtime. After you migrate the function to a supported runtime, you cannot rollback the function to the previous runtime. Phase 2 starts at least 30 days after the start of Phase 1.

See https://docs.aws.amazon.com/lambda/latest/dg/lambda-runtimes.html, though the documentation update for phase 2 is still in-progress as well.

To continue using a managed .NET Lambda runtime, we recommend upgrading to .NET 6.

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.