Error after upgrading and downgrading: Error: Method 'addPostFrameCallback' cannot be call-CodePudding

I am working on an app that uses some older dependencies and deprecated methods which I realized after upgrading to latest Flutter version.

So until i correct all of these, i downgraded back to v2.2.3 to be able to keep working on my app.

But now when i try to run i get some error that i didnt have before.

Running Gradle task 'assembleDebug'...
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/tooltip.dart:158:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/tooltip.dart:166:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/tooltip.dart:188:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((_) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/tooltip.dart:202:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((_) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/tooltip.dart:361:31: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
      WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                              ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/ballon_transition.dart:150:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/balloon.dart:56:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/balloon_positioner.dart:134:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((_) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/obfuscate_tooltip_item.dart:34:29: Error: Method 'addObserver' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addObserver(this);
                            ^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/obfuscate_tooltip_item.dart:43:29: Error: Method 'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
                            ^^^^^^^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/simple_tooltip-1.2.0/lib/src/obfuscate_tooltip_item.dart:59:29: Error: Method 'removeObserver' cannot be called on 'WidgetsBinding?' because it is potentially null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/Flutter/flutter/packages/flutter/lib/src/widgets/binding.dart').
Try calling using ?. instead.
    WidgetsBinding.instance.removeObserver(this);
                            ^^^^^^^^^^^^^^
/C:/Flutter/flutter/.pub-cache/hosted/pub.dartlang.org/carousel_slider-4.1.1/lib/carousel_slider.dart:268:7: Error: No named parameter with the name 'padEnds'.
      padEnds: widget.options.padEnds,
      ^^^^^^^
/C:/Flutter/flutter/packages/flutter/lib/src/widgets/page_view.dart:664:3: Context: Found this candidate, but the arguments don't match.
  PageView.builder({
  ^^^^^^^^^^^^^^^^


FAILURE: Build failed with an exception.

* Where:
Script 'C:\Flutter\flutter\packages\flutter_tools\gradle\flutter.gradle' line: 1035

* What went wrong:
Execution failed for task ':app:compileFlutterBuildDebug'.
> Process 'command 'C:\Flutter\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 19s
Exception: Gradle task assembleDebug failed with exit code 1

I tried changing the location and removing of "?" as suggested in other threads but it only mad it worst.

Any idea of how i could solve this issue?

CodePudding user response：

You should try the opposite. Replace

WidgetsBinding.instance.addPostFrameCallback()

with

WidgetsBinding.instance?.addPostFrameCallback()

As the error message tells you, instance might be null, so you need to safeguard it via ?

Edit: If these calls come from external dependencies, you might have no other choice than to downgrade or change these dependencies.

CodePudding user response：

Eventually got it to work. Not exactly sure why, but here's what I did.

I created a new project from the Git repo (still had the same errors)
Upgraded Flutter and dependencies (got lots of deprecation errors)
Downgraded back to 2.2.3 and re-pulled the repo version of the code > now it works

The original project is still having the same issue thought. I have no idea why one works and not the other. They are basically running the same piece of code.