A recent update saw Flutter compiles on Ubuntu broken due to an issue with lld. This was only on Flutter installed under snap. To fix it, I removed Flutter and reinstalled it from Git. There were a few issues after that so I’ve documented them here. This is the process.

First remove Flutter

sudo snap remove flutter

Then install it manually

cd ~

git clone https://github.com/flutter/flutter.git -b stable

Now modify .bashrc  (I prefer gedit but nano will do)

nano ~/.bashrc

Add this line at the end:

export PATH="$PATH:$HOME/flutter/bin"

Save it then do

source ~/.bashrc

Test the installation

flutter doctor

There may be some missing bits but this should fix them

sudo apt-get install clang cmake ninja-build pkg-config libgtk-3-dev

and repeat flutter doctor until things are ok.

Now I still had some issues

Flutter doctor told me I had a different Dart installed.

So first remove the old one

sudo snap remove dart

Check with

which dart

My configuration still had the wrong dart in it. I searched these

cat /etc/environment 
cat ~/.profile 
cat ~/.bash_profile 
cat /etc/bash.bashrc 
grep -r "dart" ~/.bashrc ~/.bash_profile ~/.profile /etc/environment /etc/bash.bashrc 2

then did

echo $PATH

Which showed no dart references so

ls -la /usr/bin/dart
which dart
sudo apt remove dart

which dart
dart --version
flutter doctor

I then found that it was trying to use a snap version of cmake

cd your_project
flutter clean
rm -rf build/
rm -rf linux/build/

and removed Cmake cache files

rm -rf linux/flutter/ephemeral/
rm linux/CMakeCache.txt 2>/dev/null

Finally I regenerated the build configuration

flutter pub get
flutter config --enable-linux-desktop
flutter create

and all was well and after adding the correct SDK path into the project files, it finally compiled on Linux again. Phew!