The Problem
After upgrading to Ubuntu 20.04, Ruby on Rails gem installations fail. If you use rvm this fails with rvm-managed environments too. Running
bundle install
bundle update
gem install
all fail.
Error Messages
You will see errors that look like this (in this case it's the byebug gem but other gems will also give the same error):
ERROR: Error installing byebug:
ERROR: Failed to build gem native extension.
make DESTDIR\= install
make: /usr/bin/mkdir: Command not found
The Solution
The problem is that Ubuntu 20.04 changes the location of the mkdir command, moving it from /usr/bin to /bin.
The easiest solution is to symbolically link the mkdir command back into /usr/bin.
- su - to root (or use sudo to execute the command below)
- ln -s /bin/mkdir /usr/bin/
Your bundle should now install as it used to.
FFI gem build failure
Another problem encountered after upgrading to Ubuntu 20.04 is that builds fail referencing the ffi gem. For example, error messags that include this text are seen:
Ignoring ffi-xxxxx because its extensions are not built
The "xxxxx" part is the ffi version number.
Simply issue this command:
gem pristine ffi
and the ffi libraries and other artefacts will be reinstated correctly, resolving the problem.
