Denbun POP V2.0P R4.3 no longer supports PostgreSQL 8.2.
The higher versions support PostgreSQL 8.3 only.
Therefore, the user who uses the version for PostgreSQL 8.2 cannot upgrade to the latest version as it is.
Please migrate the data to the version for PostgreSQL 8.3 according to this guide and upgrade the latest version of Denbun.

[The user who needs migration]
The user who use the lower version of Denbun POP V2.0P R4.3.
 ->  Upgrade it to "V2.0P R4.3" and migrate the data according to this guide.
The user who use Denbun POP V2.0P R4.3 for PostgreSQL version 8.2.
 ->  Migrate the data according to this guide.
If your version is Denbun POP V2.0P R4.3 which supports PostgreSQL 8.3, you do not have to migrate it.