database  in  use  with   active   or   pre-started   read/write
  transactions

  Explanation:  Database replication  cannot  be  started  on  the
  standby   database   if  there  are  processes  with  active  or
  pre-started read/write transactions.

  User  Action:   All  read/write  transaction  activity  must  be
  stopped  prior  to  starting database replication on the standby
  database.