I tried to play with Mongoid transactions, but an error message popped up...

Code snippet:

Project.with_session do |session|
  session.start_transaction
  Project.create!(name: 'Example')
  session.commit_transaction
end

Error:

Mongo::Error::OperationFailure: Transaction numbers are only allowed on a replica set member or mongos (20) (on :27017, legacy retry, attempt 1) (on :27017, legacy retry, attempt 1)

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