Why do I get "Unable to get IAM security credentials from EC2 Instance Metadata Service" when using SSO?

[rowanfreeman-acutro]

I followed the instructions at Token provider configuration with automatic authentication refresh for AWS IAM Identity Center to configure aws for Single Sign-On (SSO).

I verified it works by running the command aws s3 ls and it returns a list successfully.

Now in Visual Studio I'm attempting to publish my .NET Web API as a Lambda in AWS. I used the command dotnet lambda deploy-serverless <my-app> and it builds and zips but it doesn't publish because of this:

Unable to get IAM security credentials from EC2 Instance Metadata Service

Then I ran this as a test and got the same thing.

PS C:\[...]> dotnet lambda list-functions
Amazon Lambda Tools for .NET Core applications (5.8.0)
Project Home: https://github.com/aws/aws-extensions-for-dotnet-cli, https://github.com/aws/aws-lambda-dotnet

Error listing Lambda functions: Unable to get IAM security credentials from EC2 Instance Metadata Service.

In C:\Users\[Me]\.aws I have a config file that looks like this.

[default]
sso_session = development
sso_account_id = [redacted]
sso_role_name = AdministratorAccess
region = eu-central-1
output = json

[sso-session development]
sso_start_url = https://[redacted].awsapps.com/start/
sso_region = eu-central-1
sso_registration_scopes = sso:account:access

I tried running dotnet lambda list-functions --profile default but that just gives a different error:

Error listing Lambda functions: Value cannot be null. (Parameter 'Property cannot be empty: Region, StartUrl')

I also have the AWS extension for Visual Studio which I am successfully logged into via SSO.

I tried using that profile but I get the same error.

dotnet lambda list-functions --profile default-AdministratorAccess-[redacted]
Error listing Lambda functions: Value cannot be null. (Parameter 'Property cannot be empty: Region, StartUrl')

I've been on the first 20 or so Google results such as AWS DotNet SDK Error: Unable to get IAM security credentials from EC2 Instance Metadata Service but either they are about the AWS SDK (which is not what I'm doing) or they don't have any solutions that work for me.

Any ideas what I'm doing wrong?

[rowanfreeman-acutro]

This looks to have been a known issue and was fixed recently, so this problem is now resolved.

[github-actions[bot]]

Hello! Reopening this discussion to make it searchable.