最新使用Flutter 插件時，提示需要更高版本的Flutter SDK，在自動更新SDK版本之後，現有的項目各種報錯，而且又需要快速測試上線，時間緊急，所有又想辦法退回以前的SDK 版本，通過在官網上下載SDK包，然後重新配置了SDK的路徑，但是在運行項目的時候，首先會提示警號：
Warning! The 'flutter' tool you are currently running is from a different Flutter repository than the one last used by this package.
The repository from which the 'flutter' tool is currently executing will be used instead.
running Flutter tool: C:\flutter_v1.9.1_hotfix.6_stable\flutter
previous reference : C:\flutter\flutter
This can happen when you have multiple copies of flutter installed.
Please check your system path to verify that you are running the expected version (run 'flutter --version' to see which flutter is on your path).
不過大家都知道，警號這種事自動選擇忽略，所以繼續，
下面出現報錯：
Compiler message:
/C:/flutter/flutter/packages/flutter/lib/src/rendering/editable.dart:1217:3: Error: Type 'TextRange' not found.
TextRange _getNextWord(int offset) {
^^^^^^^^^
/C:/flutter/flutter/packages/flutter/lib/src/rendering/editable.dart:1228:3: Error: Type 'TextRange' not found.
TextRange _getPreviousWord(int offset) {
^^^^^^^^^
/C:/flutter/flutter/packages/flutter/lib/src/rendering/editable.dart:1246:24: Error: Type 'TextRange' not found.
bool _onlyWhitespace(TextRange range) {
^^^^^^^^^
這個信息就不得不正視了，否則程序無法運行，看提示內容，是各種包"not found",
查看一下錯誤內容，是以前的SDK路徑下的文件"not found",那就知道肯定是package 的路徑問題沒有設置正確，重新打開Setting界面，查看Flutter SDK路徑，不錯啊，是我需要的路徑，但是爲什麼還會報錯呢，這時就懷疑是程序中肯定有設置package地址的地方，所以就開始查找程序的結構，果然在程序下找到了一個.packages的文件
點擊查看裏面的內容，所引用的包的地址就是報錯的地址。
發現問題出在這裏，那就好處理了，將這個.packages包刪除，重新運行項目，OK，完美解決。