IncompleteMessage error

[GTP95]

Greetings,

I'm writing an application that has to query a "/token" endpoint of another application running on my machine and listening on port 8080. This is how I'm constructing the request:

let mut request_body = HashMap::new();
        request_body.insert("client_id", "123");
           request_body.insert("redirect_uri", "http://localhost:16515");
           request_body.insert("grant_type", "authorization_code");
           request_body.insert("code", code);
           request_body.insert("code_verifier", code_verifier);
let request = self.client.post(token_endpoint)
            .header("Shib-Spoof-Check", &self.spoof_check_secret)
            .header(self.uid_field_name.clone(), uid)
            .json(&request_body);
let response=request.send().await;

Unfortunately, I'm getting the following error:

Err(reqwest::Error { kind: Request, url: Url { scheme: "http", cannot_be_a_base: false, username: "", password: None, host: Some(Domain("localhost")), port: Some(8080), path: "/token", query: None, fragment: None }, source: hyper::Error(IncompleteMessage) })

To investigate this issue, I listened to my machine's loopback interface using Wireshark, you can find the whole capture inside
incompleteMessage.zip.
You can see the POST request to the "/token" endpoint being made in packet number 2708. But then, the very next packet sent by the same port as the one sending the previous packet (so I assume from my application) is a FIN ACK packet. So my interpretation is that it is either reqwest or hyper terminating the connection and not the server I'm talking to, is my interpretation correct? If yes, what could I do to further investigate this problem?
Thank you for your help,

GTP95

[GTP95]

I may have interpreted this the wrong way, it's likely that the client is acknowledging the server's intention to close the connection, although I wasn't able to find a FIN packet sent by the server. However, since I'm first querying a different endpoint and then the /token endpoint, it could be that the server is trying to close the previous connection after answering the first request, but reqwest is re-using the same connection as before, hence the error. Is there a way to make reqwest not reuse connections, or should I just retry the request when it fails? Note that in the current situation, the POST request to the /token endpoint always fails.

[GTP95]

Solved by retying a few times in a loop.