I'm getting this once in a while in development mode after changing the routes configuration:

ActionController::MethodNotAllowed

Only get, head, post, put, and delete requests are allowed.

The solution for me has been to restart the server.

There are at least three reasons, that I know of, to why you could be seeing mysql error 1005 (errno: 150)

• Adding a foreign key constraint when column types don't match
• Not enough privileges to execute the script
• Trying to delete an index that is needed by some other index or constraint ("error on rename of")

Use "SHOW ENGINE INNODB STATUS;" to view the error:

ALTER TABLE videos ADD constraint fk_videos_channels_id FOREIGN KEY (channel_id) REFERENCES channels (id);
SHOW ENGINE INNODB STATUS;

If you get one of these errors, it's highly likely that you've upgraded to Rails 2.2 or higher:

undefined method white_list_sanitizer' for String:Class
undefined method full_sanitizer' for String:Class

The fix is to extend the SanitizeHelper.

class String
  extend ActionView::Helpers::SanitizeHelper::ClassMethods
end

Problem:

$ svn commit -m 'xxx'
svn: Commit failed (details follow):
svn: Server sent unexpected return value (403 Forbidden) in response to MKACTIVITY request for '/svn/xxx

The solution is to specify the username:

$ svn commit -m 'xxx' --username <login>