我正在使用flutter 2.10.0运行我的桌面应用程序，并且得到了这种错误类型。
以下是我的扑动医生输出：
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 2.10.0, on Microsoft Windows [Version 10.0.19044.1766],
locale en-US)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2022 17.2.6)
[√] Android Studio (version 2021.2)
[√] IntelliJ IDEA Community Edition (version 2021.3)
[√] VS Code, 64-bit edition (version 1.69.2)
[√] Connected device (4 available)
[√] HTTP Host Availability
• No issues found!
错误如下：
20.1.58/lib/src/calendar/sfcalendar.dart(2867,31): error G7AD6136F: Method
'addPostFrameCallback' cannot be called on 'WidgetsBinding?' because it is potentially null. [E:SPACINGmarmanetForest-Inventory-Desktop-masterForest-Inventory-Desktop-masterbuildwindowsflutterflutter_assemble.vcxproj]
/C:/scr/flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_calendar-20.1.58/lib/src/calendar/sfcalendar.dart(4157,35): error G7AD6136F: Method 'addPostFrameCallback' cannot be called on 'SchedulerBinding?' because it is potentially null. [E:SPACINGmarmanetForest-Inventory-Desktop-masterForest-Inventory-Desktop-masterbuildwindowsflutterflutter_assemble.vcxproj]
/C:/scr/flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_calendar-20.1.58/lib/src/calendar/sfcalendar.dart(4176,37): error G7AD6136F: Method 'addPostFrameCallback' cannot be called on 'SchedulerBinding?' because it is potentially null. [E:SPACINGmarmanetForest-Inventory-Desktop-masterForest-Inventory-Desktop-masterbuildwindowsflutterflutter_assemble.vcxproj]
/C:/scr/flutter/.pub-cache/hosted/pub.dartlang.org/syncfusion_flutter_calendar-20.1.58/lib/src/calendar/sfcalendar.dart(4322,33): error G7AD6136F: Method 'addPostFrameCallback' cannot be called on 'SchedulerBinding?' because it is potentially null. [E:SPACINGmarmanetForest-Inventory-Desktop-masterForest-Inventory-Desktop-masterbuildwindowsflutterflutter_assemble.vcxproj]
这也是我的pubspec.yaml文件的一部分：
sdk: ">=2.12.0 <3.0.0"
dependencies:
flutter_test:
sdk: flutter
flutter:
sdk: flutter
flutter_localizations:
sdk: flutter
url_launcher: ^6.0.2
path_provider: ^2.0.1
path_provider_macos: ^2.0.0
desktop_window: 0.4.0
syncfusion_localizations: ^20.1.47
syncfusion_flutter_datagrid_export: ^20.1.47-beta
syncfusion_flutter_calendar: ^20.1.47
syncfusion_flutter_datepicker: ^20.1.47
syncfusion_flutter_charts: ^20.1.47
syncfusion_flutter_gauges: ^20.1.47
syncfusion_flutter_sliders: ^20.1.47
syncfusion_flutter_pdf: ^20.1.47-beta
syncfusion_flutter_barcodes: ^20.1.47
syncfusion_officechart: ^20.1.47-beta
syncfusion_flutter_maps: ^20.1.47
syncfusion_flutter_signaturepad: ^20.1.47
syncfusion_flutter_pdfviewer: ^20.1.47-beta
syncfusion_flutter_treemap: ^20.1.47-beta
cloud_firestore: ^3.2.1
firebase_core: ^1.19.1`
我尝试了许多没有有效输出的选项，可能有什么问题
您可以包含"？">
WidgetsBinding.instance?.addPostFrameCallback((timeStamp) { })
但我建议升级，颤振。
对于升级做flutter upgrade，使用最新版本的软件包，您可以在当前版本的上使用如下
WidgetsBinding.instance.addPostFrameCallback((timeStamp) { })
这是syncfusion_flutter_calendar包中的一个错误；他们发布了一个版本，使用的代码只能在Flutter 3.0或更高版本中使用，但没有将包的最低版本设置为Flutter 3.0。
您可以通过升级到Flutter 3.0或使用他们做出不兼容更改之前的软件包版本来解决此问题，但您也应该向软件包的开发人员报告。