class ActiveRecord::TransactionRollbackError

TransactionRollbackError will be raised when a transaction is rolled back by the database due to a serialization failure or a deadlock.

See the following:

• www.postgresql.org/docs/current/static/transaction-iso.html

• dev.mysql.com/doc/refman/5.7/en/error-messages-server.html#error_er_lock_deadlock