9.13. E985 - Error Message - The running application version (xx.xx) does not match the current database version (xx.xx)
This error message basically states that the version you have installed and are trying to run does not match the database version that the application is trying to open. This is because the database that stores all you information has been updated to the listed version in the message and cannot be opened by a previous version.
If this is on a Network Edition, this means that one or more of the other workstations that access the same database has upgraded to the version number listen in the message. You will need to install the same version on each of the workstations.
Here is why the error occurred - When the newer version was installed, the database was converted to certain changes that is not compatible with a previous version. If you have no other choice but to install this older version, you would need to uninstall the application along with the database and a new database will automatically be built, but you would lose your current information that is stored.