This issue (SD-118352) in fixed in version 14710. Post this release, these characters are handled in the migration itself. If you are planning to migrate from version less than 14610 to 14610, then you can directly migrate to 14710, to handle this ctrlz characters automatically.
In certain upgrade flow in ServicedeskPlus, (refer below table), the postgres database bundled with the product is upgraded. During this upgrade process, data from the current postgres instance will be migrated to the new upgraded postgres instance 11.17. During this process, we use PostgreSQL tools pg_dump and pg_restore, to take backup and restore data from the old to the new PostgreSQL setup.
The below trace identified from logs shows that the issue is due to the presence of ^Z(ctrl+Z) character in your database. The presence of this character in any column interferes with the execution of the data migration of the consecutive column data of the same row. To Solve this issue we need to replace the ^Z characters using English sentences or words or even space would be fine. We have created an tool to clear this problematic characters from the database in order to proceed with migration.

For older releases, such as build version less than 10500, Refer this
article to resolve this issue.
| Upgrade from version | Upgrade to Version |
Build Version < 14300 | 14300 |
Build Version < 14610 | 14610 and above |
Check whether the upgrade is a success. If the upgrade fails, a log file named ctrlZScanner.log will be created. share it with us. attach the logs folder too.