NoMethodError (undefined method `bytesize' for #<Log4r::GelfOutputter:0x000000041b09a0>):

[solars]

Hey,

I'm getting this exception:

NoMethodError (undefined method bytesize' for #<Log4r::GelfOutputter:0x000000041b09a0>): rack (1.5.2) lib/rack/utils.rb:335:inbytesize'
sinatra (1.4.3) lib/sinatra/base.rb:147:in block in finish' sinatra (1.4.3) lib/sinatra/base.rb:147:ineach'
sinatra (1.4.3) lib/sinatra/base.rb:147:in inject' sinatra (1.4.3) lib/sinatra/base.rb:147:infinish'
sinatra (1.4.3) lib/sinatra/base.rb:893:in call!' sinatra (1.4.3) lib/sinatra/base.rb:870:incall'
newrelic_rpm (3.6.8.164) lib/new_relic/rack/error_collector.rb:43:in call' newrelic_rpm (3.6.8.164) lib/new_relic/rack/browser_monitoring.rb:16:incall'
newrelic_rpm (3.6.8.164) lib/new_relic/rack/agent_hooks.rb:22:in call' rack-cache (1.2) lib/rack/cache/context.rb:136:inforward'
rack-cache (1.2) lib/rack/cache/context.rb:245:in fetch' rack-cache (1.2) lib/rack/cache/context.rb:185:inlookup'
rack-cache (1.2) lib/rack/cache/context.rb:66:in call!' rack-cache (1.2) lib/rack/cache/context.rb:51:incall'
rack (1.5.2) lib/rack/nulllogger.rb:9:in call' rack (1.5.2) lib/rack/head.rb:11:incall'
sinatra (1.4.3) lib/sinatra/base.rb:175:in call' sinatra (1.4.3) lib/sinatra/base.rb:1949:incall'
sinatra (1.4.3) lib/sinatra/base.rb:1449:in block in call' sinatra (1.4.3) lib/sinatra/base.rb:1726:insynchronize'
sinatra (1.4.3) lib/sinatra/base.rb:1449:in call' actionpack (4.0.0) lib/action_dispatch/journey/router.rb:71:inblock in call'
actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:in each' actionpack (4.0.0) lib/action_dispatch/journey/router.rb:59:incall'
actionpack (4.0.0) lib/action_dispatch/routing/route_set.rb:655:in call' newrelic_rpm (3.6.8.164) lib/new_relic/rack/error_collector.rb:43:incall'
newrelic_rpm (3.6.8.164) lib/new_relic/rack/agent_hooks.rb:22:in call' newrelic_rpm (3.6.8.164) lib/new_relic/rack/browser_monitoring.rb:16:incall'
rack-jsonp-middleware (0.0.9) lib/rack/jsonp.rb:24:in `call'

...

Does anyone know what this could be?

Versions are: Ruby 1.9.3, Rails 4, gelf (1.4.0), log4r-gelf (0.9.0)

Thanks a lot!
Christoph

[solars]

still getting this