It looks like you or your host have upgraded to the latest Rails gems.
There is a lot of discussion about the AR problems on the Rails list.
You are probably working on an old MySQL database (I'm guessing 4.0),
and using old-style passwords.
It looks like ActiveRecord 1.13.1 for some reason is now trying to
log on using the new authentication method that MySQL 4.1+ uses.
A bug has been filed for this.
In the mean time you may want to either revert your rails gems,
update the database, or perform some fu on mysql.rb 'real_connect'.






Stephan wrote:

> I'm running Ruby on Rails and MySQL on a Fedora Core 4 server. When I 
> was working on my application suddenly an error occured on all pages 
> (including pages that worked fine before). I get the following error:
> 
> #42000Access denied for user 'members'@'localhost' to database 
> 'dev_members'
> 
> I checked MySQL, but I can login with the user 'members' from localhost 
> (with the same password as in the database.yml). I can also access the 
> dev_members database and execute selects on the tables.
> 
> I also tried restarting mysql and the webserver (lighttpd), which did 
> not help.
> 
> I think the problem is in rails, but I have know idea on how to fix 
> this? Any help is appreciated...
> 
> 
> This the trace give by rails:
> ================================================================================== 
> 
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/vendor/mysql.rb:510:in 
> `read'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/vendor/mysql.rb:152:in 
> `real_connect'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/mysql_adapter.rb:45:in 
> `mysql_connection'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/abstract/connection_specification.rb:145:in 
> `connection_without_query_cache='
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/query_cache.rb:54:in 
> `connection='
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/abstract/connection_specification.rb:106:in 
> `retrieve_connection'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/connection_adapters/abstract/connection_specification.rb:20:in 
> `connection'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:931:in 
> `add_limit!'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:924:in 
> `construct_finder_sql'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/base.rb:395:in 
> `find'
> /usr/lib/ruby/gems/1.8/gems/activerecord-1.13.1/lib/active_record/deprecated_finders.rb:37:in 
> `find_all'
> #{RAILS_ROOT}/app/controllers/team_controller.rb:5:in `list'
> ================================================================================== 
> 
> 
>