Esp32 error 400 upload spiffs wav file to web server using http post

this is the python code

from flask import Flask, abort, request
from flask_cors import CORS
from tempfile import NamedTemporaryFile
import whisper
import torch
import logging


logging.basicConfig(level=logging.DEBUG)

# Check if NVIDIA GPU is available
torch.cuda.is_available()
DEVICE = "cuda" if torch.cuda.is_available() else "cpu"

# Load the Whisper model:
model = whisper.load_model("base")

app = Flask(__name__)

CORS(app)

@app.route("/")
def hello():
    return "Whisper service active!!"


@app.route('/upload', methods=['POST'])
def handler():
    if not request.files:
        # If the user didn't submit any files, return a 400 (Bad Request) error.
        abort(400)
    #    return "file not uploaded"

    # For each file, let's store the results in a list of dictionaries.
    results = []

    # Loop over every file that the user submitted.
    for filename, handle in request.files.items():
        # Create a temporary file.
        # The location of the temporary file is available in `temp.name`.
        temp = NamedTemporaryFile(delete=False)
        # Write the user's uploaded file to the temporary file.
        # The file will get deleted when it drops out of scope.
        handle.save(temp)
        # Let's get the transcript of the temporary file.
        result = model.transcribe(temp.name, language="spanish", fp16=False)
        # Now we can store the result object for this file.
        results.append({
            'filename': filename,
            'transcript': result['text'],
        })

    # This will be automatically converted to JSON.
    return {'results': results}
    

app.run(host='192.168.1.112', debug = True)