I had the same problem after this command flutter upgrade
and upgrading from V 1.22 to V 1.27.
Exactly what I did, I went to pubspec.yaml
then pub-get
& pub-upgrde
I found there’s many outdated packages then I tried pub-outdated
and the AS failed to upgrade it, the it’s suggests to me to run this command flutter pub upgrade --major-versions
and I saw that it’s successfully downloaded and installed outdated packages, Then I do Invalided Caches & restarted AS because I found it’s cached about 5GB on C partition, and finally I run the app normally again without any problems.