[Http] ClientException. Failed to Parse HTTP. 67 does not match 13.

**Steps to Reproduce**
1. Create a new project.
2. Import the package http or dio.
3. Make a simple post http request to a rest api.

**Expected results:**
1. I have executed the same rest api on postman and it worked.
2. I need execute a simple post http request, using the http package or dio.

**Actual results:**

The error occurs when execute the http.Post request, ClientException. Failed to Parse HTTP. 67 does not match 13.

The code.

Flutter doctor, I have tried resolve this issues below, but I'm managing to run the flutter except for this error

Start by reproducing the POST request with the Dart http package in a new Flutter project, using the code and Flutter doctor details shown in the issue. Compare the failing request with the working Postman request and determine what causes the HTTP parser to reject 67 versus 13; done means the request completes without ClientException.

Written by the indexing model from the issue text.