HTTPS call with error "The system cannot find the file specified"

[Daniel Hemmerling]

I got an unexpected error The system cannot find the file specified. when calling method `RoundTrip(req *Request)` from `http.Transport`.

Error occurs on a Windows 10 Enterprise (19041) maschine. Not my maschine, so no debugging.

Implementation

This go application is only a simple reverse proxy which adds TLS Client Auth.

```go

transport:= &http.Transport{

DialContext: (&net.Dialer{

KeepAlive: 1 * time.Minute,

Timeout:   1 * time.Minute,

}).DialContext,

IdleConnTimeout:       1 * time.Hour,

TLSHandshakeTimeout:   20 * time.Second,

ExpectContinueTimeout: 20 * time.Second,

ResponseHeaderTimeout: 1 * time.Minute,

MaxIdleConns:          100,

MaxIdleConnsPerHost:   4,

}

if ProxyURL != nil {

transport.Proxy = http.ProxyURL(ProxyURL)

}

transport.TLSClientConfig = &tls.Config{

Certificates: []tls.Certificate{certificate},

}

response, err := transport.RoundTrip(r)

if err != nil {

t.Logger.Errorf("Error at send to %v in %vms with error ", r.URL, elapsed.Milliseconds(), err.Error())

}

```

- `certificate` is a `tls.Certificate`

- `r` is a `*http.Request`

Error Message

```

Error at send to https://example.org:443 in 88ms with error %!(EXTRA string=The system cannot find the file specified.)

```

My guess is, that a Windows Api Call cannot find a file or registry entry, maybe while reading the  Root CAs? 

Does anyone had simlar experience and can give me a hint? How to fix the windows system; or a workaround in Go?

Link to implementation of net/http/transport.go: https://github.com/golang/go/blob/e9e0d1ef704c4bba3927522be86937164a61100c/src/net/http/transport.go#L504

Link to implementation of root CAs in windows

https://golang.org/src/crypto/x509/root_windows.go