Version 4.0.6 gets "MinIO API responded with message=Connection error:Object reference not set to an instance of an object"

When doing a upgrade from 4.0.5 to 4.06 we experienced odd behavior when using Minio client

BucketExistsAsync (and any other call)

Minio.Exceptions.ConnectionException: MinIO API responded with message=Connection error:Object reference not set to an instance of an object.. Status code=0, response=Object reference not set to an instance of an object., content=
   at Minio.MinioClient.ParseErrorNoContent(ResponseResult response) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 613
   at Minio.MinioClient.ParseError(ResponseResult response) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 596
   at Minio.MinioClient.HandleIfErrorResponse(ResponseResult response, IEnumerable`1 handlers, DateTime startTime) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 793
   at Minio.MinioClient.ExecuteTaskCoreAsync(IEnumerable`1 errorHandlers, HttpRequestMessageBuilder requestMessageBuilder, CancellationToken cancellationToken, Boolean isSts) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 574
   at Minio.BucketRegionCache.Update(MinioClient client, String bucketName) in /root/.q/sources/minio-dotnet/Minio/BucketRegionCache.cs:line 102
   at Minio.MinioClient.GetRegion(String bucketName) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 216
   at Minio.MinioClient.CreateRequest(HttpMethod method, String bucketName, String objectName, Dictionary`2 headerMap, String contentType, Byte[] body, String resourcePath) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 301
   at Minio.MinioClient.CreateRequest[T](BucketArgs`1 args) in /root/.q/sources/minio-dotnet/Minio/MinioClient.cs:line 246
   at Minio.MinioClient.BucketExistsAsync(BucketExistsArgs args, CancellationToken cancellationToken) in /root/.q/sources/minio-dotnet/Minio/ApiEndpoints/BucketOperations.cs:line 74

Connection code Interaction code

Server minio;

[okandeldev]

@CasperCBroeren, please make sure to call Build Method for minioClient Instance.

[CasperCBroeren]

@okandeldev thanks for the response. Adding the build was the fix.