Flutter – I'm with this Error in my code: Exception caught by gestures library Cannot hit test a render box with no size

Base on the code you shared, it looks like you’ve used the Expanded widget wrongly in one of the items. Here is the corrected version below. Let me know if this solved your issue.

import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';

main () {
  
  runApp(TestApp());
}

class TestApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    double deviceHeight = MediaQuery.of(context).size.height;

    return MaterialApp(
        home: Scaffold(
            backgroundColor: const Color(0xFF101d25),
            body: Center(
              child: Container(
                height: deviceHeight,
                color: const Color(0xFF101d25),
                child: Column(
                  children: [
                    const Padding(
                      padding: EdgeInsets.only(top: 110),
                      child: Text(
                        'Welcome to WhatsApp',
                        style: TextStyle(
                          fontSize: 35,
                          color: Colors.white,
                          fontWeight: FontWeight.bold,
                        ),
                        textAlign: TextAlign.center,
                      ),
                    ),
                    
                    // The change is here
                   Expanded(
                        child: Padding(
                          padding: const EdgeInsets.only(top: 70, bottom: 70),
                          child:
                          SizedBox(
                          child: Image.asset(
                            'images/image_whatsapp.jpg',
                            height: 260,
                            width: 260,
                          ),
                        ),
                      ),
                    ),
                    Padding(
                      padding: const EdgeInsets.symmetric(horizontal: 22),
                      child: RichText(
                        textAlign: TextAlign.center,
                        text: TextSpan(children: [
                          const TextSpan(
                              text: 'Read our ',
                              style:
                                  TextStyle(color: Colors.white, fontSize: 16)),
                          TextSpan(
                              text: 'Privicy Police',
                              style: const TextStyle(
                                  color: Colors.blue, fontSize: 16),
                              recognizer: TapGestureRecognizer()
                                ..onTap = () {
                                  // print('CLICK TAP ');
                                  showDialog(
                                      context: context,
                                      builder: (BuildContext context) {
                                        return AlertDialog(
                                          title: const Text('Privicy Police'),
                                          content: const Text(
                                              'This is a test to show a Alert dialog...'),
                                          actions: <Widget>[
                                            TextButton(
                                              child: const Text('Agree'),
                                              onPressed: () {
                                                Navigator.of(context).pop();
                                              },
                                            ),
                                            TextButton(
                                              child: const Text('Disagree'),
                                              onPressed: () {
                                                Navigator.of(context).pop();
                                              },
                                            )
                                          ],
                                        );
                                      });
                                }),
                          const TextSpan(
                            text: ' Tap "Agree and continue" to accept the ',
                            style: TextStyle(color: Colors.white, fontSize: 16),
                          ),
                          TextSpan(
                              text: 'Terms of Service',
                              style: const TextStyle(
                                  color: Colors.blue, fontSize: 16),
                              recognizer: TapGestureRecognizer()
                                ..onTap = () {
                                  //print('CLICK AGREE');
                                  showDialog(
                                      context: context,
                                      builder: (BuildContext context) {
                                        return AlertDialog(
                                          title: const Text('Terms of Service'),
                                          content: const Text(
                                              'This is a test to show a Alert dialog...'),
                                          actions: <Widget>[
                                            TextButton(
                                              child: const Text('Agree'),
                                              onPressed: () {
                                                Navigator.of(context).pop();
                                              },
                                            ),
                                            TextButton(
                                              child: const Text('Disagree'),
                                              onPressed: () {
                                                Navigator.of(context).pop();
                                              },
                                            )
                                          ],
                                        );
                                      });
                                }),
                          const TextSpan(
                            text: '.',
                            style: TextStyle(color: Colors.white, fontSize: 16),
                          ),
                        ]),
                      ),
                    ),
                    const SizedBox(height: 20),
                    SizedBox(
                      height: 50,
                      width: 480,
                      child: Padding(
                        padding: const EdgeInsets.symmetric(horizontal: 50),
                        child: ElevatedButton(
                            onPressed: () {
//                     _dialogBuilder(context);
                              //('AGREE AND CONTINUE');
                            },
                            style: ElevatedButton.styleFrom(
                                shape: BeveledRectangleBorder(
                                    borderRadius: BorderRadius.circular(2)),
                                backgroundColor: const Color(0xFF0ca886)),
                            child: const Padding(
                              padding: EdgeInsets.symmetric(vertical: 12),
                              child: Text(
                                'AGREE AND CONTINUE',
                                style: TextStyle(
                                    color: Color(0xFF121a21), fontSize: 16),
                              ),
                            )),
                      ),
                    ),
                    const Expanded(
                      child: SizedBox(
                        child: Column(
                          mainAxisAlignment: MainAxisAlignment.end,
                          children: [
                            Text(
                              "From",
                              style: TextStyle(color: Colors.white),
                              textAlign: TextAlign.center,
                            ),
                            Text("FACEBOOK",
                                style: TextStyle(
                                  letterSpacing: 3,
                                  color: Colors.white,
                                  fontWeight: FontWeight.bold,
                                  fontSize: 16,
                                ),
                                textAlign: TextAlign.center)
                          ],
                        ),
                      ),
                    ),
                  ],
                ),
              ),
            )));
  }
}