After i upgrade flutter from current version to latest inside my studio terminal by running flutter upgrade got following error.

```
The current Dart SDK version is 2.1.0-dev.0.0.flutter-be6309690f.

Because no versions of uri match >0.11.3 <0.12.0 and uri >=0.7.1 <0.11.3 requires SDK version >=0.8.10 <2.0.0 or >=2.0.0-dev.18 <2.0.0, uri >=0.7.1 <0.11.3-∞ or >0.11.3 <0.12.0 is forbidden.
And because uri 0.11.3 depends on quiver >=0.17.0 <0.30.0 and every version of flutter_test from sdk depends on quiver 2.0.0+1, flutter_test from sdk is incompatible with uri >=0.7.1 <0.12.0.
And because map_view 0.0.14 depends on uri ^0.11.1 and no versions of map_view match >0.0.14 <0.1.0, flutter_test from sdk is incompatible with map_view ^0.0.14.
So, because maskn depends on both map_view ^0.0.14 and flutter_test any from sdk, version solving failed.
pub get failed (1)

```

How can i solve this issue?
Any way to downgrade from latest to my older version?