AWS DotNet SDK Error: Unable to get IAM security credentials from EC2 Instance Metadata Service

I use an example from here in order to retreive a secret from AWS SecretsManager in C# code.

I have set credentials locally via AWS CLI, and I am able to retreive secret list using AWS CLI command aws secretsmanager list-secrets.

But C# console app fails with an error:

> Unhandled exception. System.AggregateException: One or more errors occurred. (Unable to get IAM security credentials from EC2 Instance Metadata Service.)
 ---> Amazon.Runtime.AmazonServiceException: Unable to get IAM security credentials from EC2 Instance Metadata Service.
   at Amazon.Runtime.DefaultInstanceProfileAWSCredentials.FetchCredentials()
   at Amazon.Runtime.DefaultInstanceProfileAWSCredentials.GetCredentials()
   at Amazon.Runtime.DefaultInstanceProfileAWSCredentials.GetCredentialsAsync()
   at Amazon.Runtime.Internal.CredentialsRetriever.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.RetryHandler.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.RetryHandler.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.CallbackHandler.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.CallbackHandler.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.ErrorCallbackHandler.InvokeAsync[T](IExecutionContext executionContext)
   at Amazon.Runtime.Internal.MetricsHandler.InvokeAsync[T](IExecutionContext executionContext)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification)
   at System.Threading.Tasks.Task`1.get_Result()
   at AWSConsoleApp2.GetSecretValueFirst.GetSecret() in D:\Work\Projects\Training\AWSConsoleApp2\AWSConsoleApp2\GetSecretValueFirst.cs:line 53
   at AWSConsoleApp2.Program.Main(String[] args) in D:\Work\Projects\Training\AWSConsoleApp2\AWSConsoleApp2\Program.cs:line 11

When I change original constructor call

IAmazonSecretsManager client = new AmazonSecretsManagerClient();

to use the constructor overload with added parameter of type AWSCredentials

IAmazonSecretsManager client = new AmazonSecretsManagerClient(new StoredProfileAWSCredentials());

it works fine.

Class StoredProfileAWSCredentials is obsolete but it works to use it. I use libraries that work without errors on the other machines and I cannot change them.

I use credentials for user that belongs to Administrators group and has full access to SecretsManager. Region has set properly in C# code, profile is default.

Any ideas? Thanks for advance