Post is not able to process DDL on target when ddl replication is turned on at source side
Check the event_log and *opo*ddl*.logs under var dir/log directory to see the last DDL issued by Post.
You can either manually fix the condition on target that causes the DDL to fail or to skip the problematic DDL.
1. Go to target where the Post stopped due to error and set the below parameter to skip the problematic DDL
sp_ctrl>set param SP_OPO_STOP_ON_DDL_ERR 0
Manually fix the problematic DDL that failed and then execute the DDL manually on target database through sqlplus.
sp_ctrl> start post
Post should skip this problematic DDL and move on.
To reset this parameter,
sp_ctrl>reset param SP_OPO_STOP_ON_DDL_ERR