Update flutter dependencies in /.pub-cache

flutter pub cache repair 

or delete /Users/xxxxxxx/development/tools/flutter/.pub-cache/hosted/pub.dartlang.org/cloud_firestore-0.8.2+3/ and run flutter packages get again.

if all the above things fail delete the cache folder or also check the version updated in the lock file (some time lock give me the problem with updating the version number)

Disclaimer: By running the command above, have a really fast internet connection or be ready to lose one hour of productive hours. ( it will redownload every package every installed on your pc, and I mean each and all of the versions of each packages)~TSR

PS: Why flutter pub cache repair download every package version previously used?


Remove the package from dependencies in pubspec.yaml, run flutter packages get. And then add the package to dependencies again and running flutter packages get.This process has solved the problem for me in the past.


The below steps worked for me.

Flutter installation corrupted
The Flutter install directory is in an inconsistent state and that causes all kinds of troubles.

Causes
Unclear

Ways to fix
Run the following commands in the Flutter install directory:

git clean -xfd
git stash save --keep-index
git stash drop
git pull
flutter doctor

Corrupted cache
Especially with plugin packages, it was seen several times that the package in the pub cache was corrupted.

Symptoms
Usually syntax errors at build time about code in dependencies.

Causes
Unknown.
IDEs or editors used by developers might not prevent editing plugin files and when they navigate into plugin code they might accidentally modify the code.

Ways to fix

Run flutter pub cache repair
This might take quite some time and re-downloads every package in the cache, even outdated versions that might not be used anymore by any project on disk.

Delete ~/.pub-cache/hosted and/or ~/.pub-cache/git (for Git dependencies). This requires running flutter packages to get in all active projects on your machine afterward.

Delete a specific package or package version. Look up the exact path in the cache for a specific package in the .packages file of your project. For example for firebase_auth

Reference: https://github.com/flutter/flutter/wiki/Workarounds-for-common-issues#flutter-installation-corrupted