I am running OS X 10.5, Ruby 1.8.6, Rails 2.1, and sqlite3-ruby 1.2.2 and I get the following error when trying to rake db:migrate on an app that works find connected to MySQL.

rake aborted! no such file to load -- sqlite3/database

+2  A: 

Looks like there's a bug with 1.2.2. Just roll back to 1.2.1 with:

gem install sqlite3-ruby -v=1.2.1

and that will fix the problem.

go minimal

Sqlite rules :D

Shawn Simon
+2  A: 

Jamis has just released 1.2.4, and the comment history on that bug suggests that the fix is in 1.2.3 and later versions. As a quick test, I did the following on an OS X 10.5 box with Ruby 1.8.6:

sudo gem install sqlite3-ruby

(verified version number of 1.2.4)

rails test

(used default database.yml with sqlite3)

cd test
./script/generate model Person name:string
rake db:migrate

Ran fine. The error would have happened when sqlite3 was required before the migration finished, so it looks like they've fixed the issue.