Your clone encountered an issue in preflight checks due to an invalid data preserver or exclude table record.

The clone message below occurred, e.g., because a database view was added to the list of data preservers:

Release or Environment

London, Madrid, New York, Orlando


Before adding data preservers or exclude records on the source instance, please review this checklist that summarizes the preflight checks that are performed by the system, and that can prevent a clone from completing.

 Don't create a data preserver on this table


sys_counter_numberduplicate numbers would result
sys_attachmentthe large table size in the target can cause a failure
pa_favoritesnot supported
any database view 

A database view is a virtual table that is built in real time when the table is displayed. The records don't exist in the system as a physical table.

Examples of common out-of-box database views that cannot be specified in a data preserver list:



In addition, these are rare database configuration issues that can prevent a clone from succeeding:

A table name that is in upper case must first be changed to lower case.

A schema mismatch error can occur if the COLUMN_TYPE of a table has been changed on the source or target instance within a few days of the clone, e.g., from "varchar(40)" to "mediumtext".


Remember that if you exclude a table in a clone, the system will create an empty but usable table on the target instance.

Excluding a system table that starts with "sys_" can result in an unusable target instance. For example, if you mistakenly exclude the  sys_plugins table so that no plugins are present on the clone target, then the normal system activities will not function; the clone target will loop with the message "Establishing Session...", and no user will be able to log in. 

Please see this link for 'exclude table' constraints, two of which are

  1. the clone will fail during a clone's Preflight check if the sys_user or sys_user_has_role tables are added to the clone exclude list.
  2. if the sys_properties table is added to the clone exclude list, the clone will complete but the target instance's configuration and UI properties will be incorrect.

KB0712483 - Tables that should not be added to the Clone exclude list.


Before adding a data preserver or exclude table, review the checklist above to ensure that the preflight checks will run smoothly, and your clone will complete.

Article Information

Last Updated:2020-04-15 02:28:48