Library not loaded: libpq.5.dylib

Question

I have app that is running Ruby 1.9.2, Rails 3, and postgreSQL 8.3. It was originally setup and working with postgreSQL 9.1, but I uninstalled 9.1 and installed and changed to 8.3 insure compatibility on a Heroku shared database setup. It was running ok, but it's not now

Now, when working on this app, when I run a database upgrade I get this error:

dlopen(/Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle, 9): Library not loaded: libpq.5.dylib
  Referenced from: /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle
  Reason: no suitable image found.  Did find:
    /usr/lib/libpq.5.dylib: no matching architecture in universal wrapper - /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle

And when I try to run the server I get this error message:

/Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg.rb:4:in `require': dlopen(/Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle, 9): Library not loaded: libpq.5.dylib (LoadError)
  Referenced from: /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle
  Reason: no suitable image found.  Did find:
    /usr/lib/libpq.5.dylib: no matching architecture in universal wrapper - /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg_ext.bundle
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/pg-0.12.2/lib/pg.rb:4:in `<top (required)>'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `require'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `each'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:66:in `block in require'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `each'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler/runtime.rb:55:in `require'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290@global/gems/bundler-1.0.21/lib/bundler.rb:122:in `require'
    from /Users/michaeljmccoy/www/mikemccoy/config/application.rb:7:in `<top (required)>'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.0.rc2/lib/rails/commands.rb:53:in `require'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.0.rc2/lib/rails/commands.rb:53:in `block in <top (required)>'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.0.rc2/lib/rails/commands.rb:50:in `tap'
    from /Users/michaeljmccoy/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.0.rc2/lib/rails/commands.rb:50:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'

I know they are very similar errors and probably has to do with a missing path. However, when I add the path to my .profile file and restart the terminal window, I get the same errors.

Answer 1

You may need to remove and re-install the pg gem, so it's compiled against the correct version of Postgres.

Answer 2

For anyone seeing this error and running PostgresApp, this is a known problem that was fixed in version 9.2.4.3:

Discussion: https://github.com/PostgresApp/PostgresApp/issues/109

Installer: https://github.com/PostgresApp/PostgresApp/releases/tag/9.2.4.3

Of course, you could just grab the latest version (http://postgresapp.com/). Both versions got me back up and running with Rails 3.2.14 and Ruby 2.0.0. However, note that when I installed 9.2.4.3 my databases were still listed in psql, but when I installed 9.3.0 (the current version at the moment), my databases were no longer listed.