<form action="/upload" method="post" enctype="multipart/form-data">
                          <label for="pdfformmail{{indexfile}}">Загрузить</label>
                          <input enctype type="file" onChange=selectFile(this)  name="pdfformmail" id="pdfformmail{{indexfile}}">
                        </form>

 from fastapi import FastAPI, Request,UploadFile, File
import webbrowser
.....
@app.post("/upload")
def upload_file(file: UploadFile):
      return file