heroku db: push throws «Taps Server Error: undefined method` symbolize_keys 'for nil: NilClass »

Я в процессе перехода на хостинг Heroku. У меня есть на моем локальном компьютере копия текущей производственной базы данных (> 100 M), и я не могу отправить ее на heroku.

Я снова и снова получаю одну и ту же ошибку:

Taps Server Error: undefined method `symbolize_keys' for nil:NilClass

Похоже, это связано с некоторыми значениями NULL в базе данных (не со всеми). Есть какие нибудь идеи как это починить? Спасибо!

Вот полный вывод:

!!! Caught Server Exception
HTTP CODE: 500
Taps Server Error: undefined method `symbolize_keys' for nil:NilClass
/app/lib/taps/data_stream.rb:183:in `parse_json'/app/lib/taps/server.rb:69:in 
POST /sessions/:key/push/verify_stream /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:863:in
call/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:863:in 
route /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:521:in
instance_eval /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:521:in
route_eval /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:500:in 
route!/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:497:in 
catch/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:497:in 
route!/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:476:in 
each/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:476:in 
route!/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:601:in 
dispatch! /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:411:in
call! /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in 
instance_eval /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in
invoke/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in 
catch /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:566:in
invoke /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:411:in
call!/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:399:in 
call/app/.bundle/gems/ruby/1.8/gems/rack-1.2.1/lib/rack/auth/basic.rb:25:in 
call /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:979:in 
call /app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:1005:in 
synchronize/app/.bundle/gems/ruby/1.8/gems/sinatra-1.0/lib/sinatra/base.rb:979:in
call/home/heroku_rack/lib/static_assets.rb:9:in 
call'/home/heroku_rack /lib/last_access.rb:15:in 
call'/app/.bundle/gems/ruby/1.8/gems/rack-1.2.1/lib/rack/urlmap.rb:47:in 
call'/app/.bundle/gems/ruby/1.8/gems/rack-1.2.1/lib/rack/urlmap.rb:41:in 
each'/app/.bundle/gems/ruby/1.8/gems/rack-1.2.1/lib/rack/urlmap.rb:41:in 
call'/home/heroku_rack/lib/date_header.rb:14:in 
call'/app/.bundle/gems/ruby/1.8/gems/rack-1.2.1/lib/rack/builder.rb:77:in 
call'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/connection.rb:76:in         
pre_process'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/connection.rb:74:in 
catch'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/connection.rb:74:in       
pre_process'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/connection.rb:57:in
process'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/connection.rb:42:in     
receive_data'/app/.bundle/gems/ruby/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in 
run_machine'/app/.bundle/gems/ruby/1.8/gems/eventmachine-0.12.10/lib/eventmachine.rb:256:in 
run'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/backends/base.rb:57:in 
start'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/server.rb:156:in 
start'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/controllers/controller.rb:80:in 
start'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/runner.rb:177:in 
send'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/runner.rb:177:in 
run_command'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/lib/thin/runner.rb:143:in 
run!'/app/.bundle/gems/ruby/1.8/gems/thin-1.2.7/bin/thin:6/usr/ruby1.8./bin/thin:19:in  
load'/usr/ruby1.8.7/bin/thin:19