App not working after creating apk

[mahmud al hasan]

I have created a kivy signup app with MySQL database. To send data I have used json and rest api. Now, my application works well on desktop but stops working after I create apk. 
When I press the login button it stops working. 

Here is my code for signup- 

from kivy.uix.boxlayout import BoxLayout

import requests, json, urllib3

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

class SignupPage(BoxLayout):

    def signup(self):

        username, password = self.ids.username.text, self.ids.password.text

        info = {

            "signup": [

                {

                    "username": username,

                    "password": password

                }

            ]

        }

        # headers = {"Content-type": "application/json"}

        url = 'https://talhatraining.org/signup/signup.php'

        resp = requests.post(url, data=dict(info=json.dumps(info)), verify=False)

        if resp:

            if  username and password:

                print('Data successfully saved!')

            else:

                print('Please enter user name and password!')