Flutter Upgrade Issue
The error seems to be quite clear.
Your latest version of mockito needs the higher version of code_builder but your build_runner version is too low to support it.
There is a later version of build_runner available, which is build_runner: ^2.0.3 which supports code_builder: ^4.0.0.
So, in your pubsec.yaml, just change your build_runner version to ^2.0.3 wherever you have it.
That should be fixing it.
This is a dependency issues, one by one check errors and change the library versionfor example enter link description here version
flutter pub get#check error#replace that library with higher or lower version accordingly#After updateflutter pub get