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:into_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:ininsert’
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:increate’
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:inblock 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:inrun_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:increate_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:insave’
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:inblock (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:intransaction’
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:inwith_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:inrollback_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:instart’
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'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.