Installing Ruby on Rails latest version matching Ruby 3.0

Question

When I try the following, after installing Ruby 3.0 from snap on Ubuntu 18.04::

gem install rails

I get this error:

/snap/ruby/201/lib/ruby/3.0.0/x86_64-linux/rbconfig.rb:13:in `<module:RbConfig>': ruby lib version (3.0.0) doesn't match executable version (2.5.1) (RuntimeError)

It was right after using

rails new rest-api-messages --api --database=postgresql

and trying to install PostGRES

gem install pg -v '1.2.3' --source 'https://rubygems.org/'

How could I solve this? is Ruby on Rails only for version 2.5.1 and lower?

edit: Then I got

Can't find the 'libpq-fe.h header when trying to install pg gem

Solved with

sudo apt-get install libpq-dev

Duplicate from Can't find the 'libpq-fe.h header when trying to install pg gem

score 2 · Accepted Answer · answered Mar 24 '21 at 20:02

2

My guess is you already had Ruby 2.5 installed and they are stepping on each other. Ruby versions don't overwrite each other. You need to uninstall Ruby 3.0 and 2.5 and install a Ruby version manager then install Ruby using it. This will also give you a path to move forward easily. Check out Ruby version manager like rbenv or RVM. Take a look at both. For what it's worth. I have used both and finally settled on rbenv.

answered Mar 24 '21 at 20:02

Mike Chilson

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I had it installed with apt-get and then removed it – Antonin GAVREL Mar 24 '21 at 20:03
There is a version of ruby already install on Ubuntu. It has to be removed first. – Mike Chilson Mar 24 '21 at 20:06
`sudo apt-get remove gem` have done this but now I get `mkmf.rb can't find header files for ruby at /usr/lib/ruby/include/ruby.h` when trying to install pg with gem – Antonin GAVREL Mar 24 '21 at 20:08
Also, I would not be installing Ruby from snaps. Use one of the Ruby version managers to install the version you need. – Mike Chilson Mar 24 '21 at 20:09
Run Ruby -v and see what happens. If you get an answer you still have a version installed. – Mike Chilson Mar 24 '21 at 20:09
If not... Then install one of the Ruby Version managers, then use it to install Ruby 3.0 – Mike Chilson Mar 24 '21 at 20:12
Here is a step-through article on how to do it. https://www.digitalocean.com/community/tutorials/how-to-install-ruby-on-rails-with-rbenv-on-ubuntu-18-04 – Mike Chilson Mar 24 '21 at 20:13
it worked to install cleanly ruby and rails with latest version changed to 3.0.0 and 6.1.3 but still get the error for postgresql: missing `fatal error: libpq-fe.h: No such file or directory` – Antonin GAVREL Mar 24 '21 at 21:35
Edit: its a duplicate, vote to close, appreciate the help though! Thanks Mike! – Antonin GAVREL Mar 24 '21 at 21:40

Installing Ruby on Rails latest version matching Ruby 3.0

1 Answers1