# Upgrading to Sidekiq 3.0
Sidekiq 3.0 brings several new features but also removes old APIs and
changes a few data elements in Redis. To upgrade cleanly:
* Upgrade to the latest Sidekiq 2.x and run it for a few weeks.
`gem 'sidekiq', '< 3'`
This is only needed if you have retries pending.
* 3rd party gems which use **client-side middleware** will need to update
due to an API change. The Redis connection for a particular job is
passed thru the middleware to handle sharding where jobs can
be pushed to different redis server instances.
`def call(worker_class, msg, queue, redis_pool)`
Client-side middleware should use `redis_pool.with { |conn| ... }` to
perform Redis operations and **not** `Sidekiq.redis`.
* If you used the capistrano integration, you'll need to pull in the
new [capistrano-sidekiq](https://github.com/seuros/capistrano-sidekiq)
gem and use it in your deploy.rb.
* API changes:
- `Sidekiq::Client.registered_workers` replaced by `Sidekiq::Workers.new`
- `Sidekiq::Client.registered_queues` replaced by `Sidekiq::Queue.all`
- `Sidekiq::Worker#retries_exhausted` replaced by `Sidekiq::Worker.sidekiq_retries_exhausted`
- `Sidekiq::Workers#each` has changed significantly with a reworking
of Sidekiq's internal process/thread data model.
* `sidekiq/api` is no longer automatically required. If your code uses
the API, you will need to require it.
* Redis-to-Go is no longer transparently activated on Heroku so as to not play
favorites with any particular Redis service. You need to set a config option
for your app:
`heroku config:set REDIS_PROVIDER=REDISTOGO_URL`. You may also use
the generic `REDIS_URL`. See
[Advanced Options: Setting the Location of your Redis server][1]
for details.
* Anyone using Airbrake, Honeybadger, Exceptional or ExceptionNotifier
will need to update their error gem version to the latest to pull in
Sidekiq support. Sidekiq will not provide explicit support for these
services so as to not play favorites with any particular error service.
* MRI 1.9 is no longer officially supported. Sidekiq's official
support policy is to support the current and previous major releases
of MRI and Rails. As of February 2014, that's MRI 2.1, MRI 2.0, JRuby 1.7, Rails 4.0
and Rails 3.2. I will consider PRs to fix issues found by users for
other platforms/versions.
## Error Service Providers
If you previously provided a middleware to capture job errors, you
should instead provide a global error handler with Sidekiq 3.0. This
ensures **any** error within Sidekiq will be logged appropriately, not
just during job execution.
```ruby
if Sidekiq::VERSION < '3'
# old behavior
Sidekiq.configure_server do |config|
config.server_middleware do |chain|
chain.add MyErrorService::Middleware
end
end
else
Sidekiq.configure_server do |config|
config.error_handlers << Proc.new {|ex,context| MyErrorService.notify(ex, context) }
end
end
```
Your error handler must respond to `call(exception, context_hash)`.
[1]: https://github.com/mperham/sidekiq/wiki/Advanced-Options#via-env-variable