NoMethodError: undefined method `accept' for nil:NilClass

Here’s the trace,

NoMethodError: undefined method `accept’ for nil:NilClass

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/connection_adapters/abstract/database_statements.rb:7:in `to_sql'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/connection_adapters/abstract/database_statements.rb:89:in `insert'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/connection_adapters/abstract/query_cache.rb:14:in `insert'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/relation.rb:66:in `insert'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/persistence.rb:363:in `create'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/timestamp.rb:57:in `create'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/callbacks.rb:268:in `block in create'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:403:in `_run__3940325652772678349__create__4360101769414794529__callbacks'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:405:in `__run_callback'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:385:in `_run_create_callbacks'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:81:in `run_callbacks'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/callbacks.rb:268:in `create'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/persistence.rb:344:in `create_or_update'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/callbacks.rb:264:in `block in create_or_update'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:403:in `_run__3940325652772678349__save__4360101769414794529__callbacks'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activesupport-3.2.3/lib/active_support/callbacks.rb:405:in `__run_callback'

… 4 levels…

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/validations.rb:50:in `save'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/attribute_methods/dirty.rb:22:in `save'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:241:in `block (2 levels) in save'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:295:in `block in with_transaction_returning_status'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:208:in `transaction'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:293:in `with_transaction_returning_status'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:241:in `block in save'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:252:in `rollback_active_record_state!'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/activerecord-3.2.3/lib/active_record/transactions.rb:240:in `save'

from (irb):7

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.3/lib/rails/commands/console.rb:47:in `start'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.3/lib/rails/commands/console.rb:8:in `start'

from /Users/blaine/.rvm/gems/ruby-1.9.2-p290/gems/railties-3.2.3/lib/rails/commands.rb:41:in `<top (required)>'

from script/rails:6:in `require'

from script/rails:6:in `<main>'ruby-1.9.2-p290 :008 > ^D

From other sources on the web I found I should run the following,

$ bundle update activerecord-mysql2-adapter mysql2

I had the latest versions of these gems already, but I get the same error.

I fixed the problem by removing activerecord-mysql2-adapter from my Gemfile and using only mysql2.