showing Error while running using Getx widget-Flutter - flutter

Question

This error occurs only when I use get package. To Solve this problem, I deleted get folder from the .pub-cache/hosted/pub.dartlang.org destination and again imported it but nothing happened.
Launching lib\main.dart on sdk gphone x86 arm in debug mode...
Running Gradle task 'assembleDebug'...
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_cupertino_app.dart:121:9:
Error: Type 'RouteInformationProvider' not found.
final RouteInformationProvider routeInformationProvider;
^^^^^^^^^^^^^^^^^^^^^^^^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_cupertino_app.dart:122:9: Error: Type
'RouteInformationParser' not found.
final RouteInformationParser<Object> routeInformationParser;
^^^^^^^^^^^^^^^^^^^^^^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_cupertino_app.dart:122:9: Error:
Expected 0 type arguments.
final RouteInformationParser<Object> routeInformationParser;
^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_cupertino_app.dart:123:9: Error: Type
'RouterDelegate' not found.
final RouterDelegate<Object> routerDelegate;
^^^^^^^^^^^^^^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_cupertino_app.dart:123:9: Error:
Expected 0 type arguments.
final RouterDelegate<Object> routerDelegate;
^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_material_app.dart:130:9: Error:
Expected 0 type arguments.
final RouteInformationParser<Object> routeInformationParser;
^^^^^^^^^^^^^^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_material_app.dart:132:9: Error: '
BackButtonDispatcher' isn't a type.
final BackButtonDispatcher backButtonDispatcher;
^^^^^^^^^^^^^^^^^^^^
/D:/Flutter/.pub-cache/hosted/pub.dartlang.org/get-3.25.4/lib/
get_navigation/src/root/get_material_app.dart:245:25: Error:
Method not found: 'MaterialApp.router'.
? MaterialApp.router(
^^^^^^
FAILURE: Build failed with an exception.
* Where:
Script 'D:\Flutter\packages\flutter_tools\gradle\flutter.gradle'
line: 896
* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'D:\Flutter\bin\flutter.bat'' finished with non
-zero exit value 1
* Try:
Run with --stacktrace option to get the stack trace. Run with --
info or --debug option to get more log output. Run with --scan to
get full insights.
* Get more help at https://help.gradle.org
BUILD FAILED in 22s
Exception: Gradle task assembleDebug failed with exit code 1
I Used many other packages but the error occurred only when using get package.

Answer 1

open your android studio terminal
1 - clean your project
flutter clean
2 - change flutter channel to stable
Flutter channels:
master
dev
beta
* stable
make sure you are on a stable channel
3 - now you need to make upgrade flutter upgrade (on the terminal)
flutter upgrade
output
Flutter is already up to date on channel stable
Flutter 2.0.1 • channel stable • https://github.com/flutter/flutter.git
Framework • revision c5a4b4029c (2 days ago) • 2021-03-04 09:47:48 -0800
Engine • revision 40441def69
Tools • Dart 2.12.0
4 - make clean again
flutter clean
if you on flutter 2 then all is well :)