How to handle Ruby on Rails error: "Please install the postgresql adapter: `gem install activerecord-postgresql-adapter'"

Question

Running a Ruby on Rails (RoR) app or Ruby code which uses the ActiveRecord framework, you get the error message:

Please install the postgresql adapter: gem install activerecord-postgresql-adapter

Trying to run:

gem install activerecord-postgresql-adapter

also fails, leaving you at a loss.

My attempts at following that post are included in my original answer, as they did not work for me. — user71268
– user71268, Commented Nov 2, 2009 at 23:32

Mike Blyth · Accepted Answer · 2013-04-06 07:58:13Z

128

The problem is not what anyone wrote. The problem is that the name of the postgresql database adapter is "postgresql", not "postgres", though the name of the GEM is "pg".

The definition in the database.yml file should include

  adapter: postgresql

edited Apr 6, 2013 at 7:58

Mike Blyth

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answered Jun 29, 2010 at 22:03

mcr

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5 Comments

carl crott Over a year ago

Is this something that could be fixed fairly easily? I mean so that the names are corrected and error messages appropriate?

boulder_ruby Over a year ago

Please install the postgres adapter: gem install activerecord-postgres-adapter

stack1 Over a year ago

what if i am just using ruby and not ror ? I can't find any datbase.yml file

stack1 Over a year ago

@boulder_ruby - ERROR: Could not find a valid gem 'activerecord-postgres-adapter' (>= 0) in any repository.

ChumiestBucket Over a year ago

@boulder_ruby that gem doesn't exist lmao

jstreebin · Accepted Answer · 2011-12-10 00:25:48Z

10

Here's the answer I got from Heroku and it worked for me (after trying different pg gems, adapters, and everything else on the 10 other posts about this)

1) add the line: gem 'pg' to your Gemfile.

2) Run the command bundle install to install the gem into your bundle.

3) Stage the Gemfile and Gemfile.lock changes: git add Gemfile Gemfile.lock

4) Commit the changes: git commit -m "Install the pg gem"

5) Redeploy to heroku: git push heroku master

answered Dec 10, 2011 at 0:25

jstreebin

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Comments

user71268 · Accepted Answer · 2009-11-02 23:30:58Z

9

This means you don’t have the new ‘pg’ postgresql library installed. This is easily fixed with a bit of:

sudo gem install pg

I (Dov) found other solutions on the web which described setting GEM_HOME and adding ~/.gem/ruby/vers/bin to your PATH, but they didn't work. This solution above was provided by Mark Mansour on his blog State of Flux at: http://stateofflux.com/2008/7/13/activerecord-postgresql-adapter-in-rails-2-1/

answered Nov 2, 2009 at 23:30

user71268

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2 Comments

Toby Hede Over a year ago

This one did not work for me ... still looking for a solution.

Steven Soroka Over a year ago

I don't recommend installing gems with sudo. Better yet, use Bundler.

Chad · Accepted Answer · 2013-09-25 04:40:32Z

6

There is one more deeply hidden condition that will also cause this error.

If you have a local environment variable DATABASE_URL=postgres://mehmehmeh set, then some gem (I suspect Heroku) causes the app to think that Postgres is required even if it's nowhere in your configs. Kill that env variable and you should be fine.

answered Sep 25, 2013 at 4:40

Chad

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4 Comments

mike Over a year ago

This was my problem. Tricky!

Andrei Puf Over a year ago

Really useful for me as well. I was not using pstgresql anywhere in my project but an old DATABASE_URL environment variable was there hiding and causing this.

Sachin Gevariya Over a year ago

Thank you very much. I was facing this issue till last 3 days. And finally found an answer from you @chad. Thanks again.

user341493 Over a year ago

I was getting a bizaar error about the Active Record 'http' Adapter that was caused by this environment variable being in my .env. Glad I finally found this post!

Doug · Accepted Answer · 2012-09-27 00:58:58Z

2

Check database.yml environment db is correct. If it is postgresql, you might need to change it to refer to mysql2 or whatever db your using for your given environment.

answered Sep 27, 2012 at 0:58

Doug

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Comments

Paolo Bernasconi · Accepted Answer · 2012-11-28 01:33:12Z

2

You can try this

On debian(squeeze):

aptitude install libdbd-pg-ruby

edited Nov 28, 2012 at 1:33

Paolo Bernasconi

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answered Mar 6, 2011 at 7:19

Daniel134

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Comments

KurtB · Accepted Answer · 2010-10-22 07:32:25Z

1

sudo apt-get install ruby1.8-dev

then...

gem install pg

Worked for me!

answered Oct 22, 2010 at 7:32

KurtB

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1 Comment

Ramon Tayag Over a year ago

What if we want to use 1.9.2?

tomcopeland · Accepted Answer · 2009-11-04 00:18:27Z

0

I did a little roundup of the current state of Ruby + PostgreSQL database drivers on railsonpostgresql.com; I think sudo gem install pg is probably the one you want.

answered Nov 4, 2009 at 0:18

tomcopeland

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1 Comment

Nick Zalutskiy Over a year ago

Thank you. I was looking for the difference between different drivers. Information not as easy to find as I thought.

Viet Pham · Accepted Answer · 2013-05-30 18:33:31Z

While trying out different search results, I installed a bunch. What finally got my environment to stop complaining with this message: "Please install the postgresql adapter: gem install activerecord-postgresql-adapter" was:

I removed all gems relating to the adapter such as: sudo gem uninstall activerecord-jdbc-adapter; sudo gem uninstall activerecord-jdbcpostgresql-adapter; sudo gem uninstall activerecord-postgresql-adapter; sudo gem uninstall jdbc-postgres;
I also removed references to adapter as followed inside my Gemfile: gem 'activerecord-jdbcpostgresql-adapter'
Leave only pg (0.15.1) installed (to check for existence of pg, do "gem list")

Then running "rake db:create" works. So, I guess pg is the latest and works. However, it does not get used when other broken adapter gems are around.

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