Request how to implement Shotgrid upload with REST API

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1

Hi.
I’m currently developing a file upload page and I want to receive the FormData (file to be uploaded) delivered from the front to the back end and upload it directly to the ‘sg_multi_files’ field of Shotgrid’s ‘Task’ entity with the REST API.
I managed to get the Upload URL by receiving the Shotgrid API token through the Shotgrid REST API guide.
The ‘storage_service’ I received is of the ‘s3’ type, but I don’t know how to upload it.

for file in uploaded_files:
    if file.filename != '':
        data = file.read()
        ####### Get Upload URL
        headers = {
            'Accept': 'application/json',
            'Authorization': f'Bearer {access_token}'
        }
        get_upload = requests.get(f'{rest_url}/entity/Task/{sel_task_id}/{field_name}/_upload', params={'filename':{file.filename}},
                                headers=headers)
        response = get_upload.json()
        upload_url = response['links']['upload']
        complete_url = response['links']['complete_upload']

        ####### Put Upload
        headers = {
            'Content-Type': file.content_type,
            # 'Content-Type': 'image/*',
            'x-amz-meta-original-filename': file.filename,
            # 'x-amz-acl': 'public-read'
        }
        upload_file = requests.put(upload_url, data=data, headers=headers)

        ####### Post Upload
        headers = {
            'Content-Type': 'application/json',
            'Accept': 'application/json',
            'Authorization': f'Bearer {access_token}'
        }
        data = {
            'upload_info': response['data'],
            'links': response['links'],
            'upload_data': {
                'display_name': file.filename
            }
        }
        complete_upload = requests.post(site_url+complete_url,headers=headers,data=data)

The above source is something I searched on the Internet and implemented
I am receiving 403 response from upload_file which is a put request
The post request, complete_upload, is responding to 500.

I’m so desperate for help right now