Redis EXECABORT Transaction discarded because of previous errors. (Redis::CommandError)

I also encountered this error when hitting maxmemory on that redis instance.

You can test it on your dev box by setting maxmemory (ie.. in /usr/local/etc/redis.conf) to sthg small e.g.

 maxmemory 3MB

Then fill up your redis with a bunch of data, start Sidekiq, and watch the fireworks

    2014-02-03T14:32:30Z 59365 TID-ov2cb18yw WARN: {"retry"=>true, "queue"=>"default", "backtrace"=>true, "class"=>"MailWorker", "args"=>["Profile::Created", 868], "jid"=>"d7b0589736818c2ffcd58c90", "enqueued_at"=>1391437950.4245608}
    2014-02-03T14:32:30Z 59365 TID-ov2cb18yw WARN: EXECABORT Transaction discarded because of previous errors.
    2014-02-03T14:32:30Z 59365 TID-ov2cb18yw WARN: /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis/pipeline.rb:76:in `finish'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis/client.rb:121:in `block in call_pipeline'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis/client.rb:243:in `with_reconnect'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis/client.rb:119:in `call_pipeline'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis.rb:2077:in `block in multi'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis.rb:36:in `block in synchronize'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/1.9.1/monitor.rb:211:in `mon_synchronize'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis.rb:36:in `synchronize'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-3.0.4/lib/redis.rb:2069:in `multi'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-namespace-1.3.1/lib/redis/namespace.rb:337:in `namespaced_block'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/redis-namespace-1.3.1/lib/redis/namespace.rb:224:in `multi'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/sidekiq-2.13.1/lib/sidekiq/processor.rb:93:in `block in stats'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/connection_pool-1.1.0/lib/connection_pool.rb:49:in `with'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/sidekiq-2.13.1/lib/sidekiq.rb:67:in `redis'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/sidekiq-2.13.1/lib/sidekiq/util.rb:25:in `redis'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/sidekiq-2.13.1/lib/sidekiq/processor.rb:92:in `stats'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/sidekiq-2.13.1/lib/sidekiq/processor.rb:46:in `block in process'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `call'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `public_send'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/calls.rb:25:in `dispatch'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/calls.rb:67:in `dispatch'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/future.rb:15:in `block in new'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/internal_pool.rb:59:in `call'
    /usr/local/opt/rbenv/versions/1.9.3-p392/lib/ruby/gems/1.9.1/gems/celluloid-0.14.1/lib/celluloid/internal_pool.rb:59:in `block in create'

I resolved this by doing a FLUSHALL, which cleared out all the data from the redis instance. It appears that somewhere along the way the data got corrupted, and that fixed it.