Here is something I have tried. When we browse the bloburl, it has the pdf data with all modifications. when I try to upload the blob file to server the file is corrupted. I can't open it in pdf viewer. when I try to open the saved file in server using chrome, it opens and only the modified data is showing. All other content are corrupted.

Please suggest any method you see fit.

var blobUrl = "blob:http://localhost/6e28b1f8-65c2-4457-a8f6-bffaab5f2347";
const data = await fetch(blobUrl);            
const blob = await data.blob();       

var formData = new FormData();   
formData.append("file", blob,"filename.pdf");

await fetch('http://localhost:54402//Controller//Methode', {
    method: 'POST',
    body: formData
})
.then(response => response)
.then(data => console.log(data));

C#

public ActionResult Methode(HttpPostedFileBase file)
    {

    }