我有一个Rails应用程序，试图通过Mongoid连接到MongoDB Atlas集群（v3.6）。我一直遇到这个错误：
[ERROR] Cannot start transaction 4 on session c6e79139-1be1-4c1c-9d13-a5e7ca45c792 - X6aX2zlpqRGB3UhpvFsz7wCO85u1m8A5+nkcYk7NDoM= because a newer transaction 30 has already started. (225)
[ERROR] /home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/operation/result.rb:267:in `raise_operation_failure'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/operation/result.rb:263:in `validate!'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/operation/shared/write.rb:42:in `execute'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/collection/view/writable.rb:307:in `block (2 levels) in update_one'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/retryable.rb:133:in `write_with_retry'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/collection/view/writable.rb:295:in `block in update_one'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/cluster.rb:655:in `with_session'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/client.rb:662:in `with_session'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/collection/view.rb:204:in `with_session'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/mongo-2.7.0/lib/mongo/collection/view/writable.rb:294:in `update_one'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/bundler/gems/mongoid-9afa64b7b0c0/lib/mongoid/query_cache.rb:182:in `update_one_with_clear_cache'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/bundler/gems/mongoid-9afa64b7b0c0/lib/mongoid/persistable/updatable.rb:144:in `block in update_document'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/bundler/gems/mongoid-9afa64b7b0c0/lib/mongoid/persistable/updatable.rb:118:in `block (2 levels) in prepare_update'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:117:in `call'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:555:in `block (2 levels) in compile'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:505:in `call'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:92:in `__run_callbacks__'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:778:in `_run_update_callbacks'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/gems/activesupport-4.2.11/lib/active_support/callbacks.rb:81:in `run_callbacks'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/bundler/gems/mongoid-9afa64b7b0c0/lib/mongoid/interceptable.rb:138:in `run_callbacks'
/home/dev/.rvm/gems/ruby-2.4.4@myproj/bundler/gems/mongoid-9afa64b7b0c0/lib/mongoid/persistable/updatable.rb:117:in `block …