VPOP3 v8.x uses PostgreSQL 10 as its database engine, which is the latest supported 32 bit version of PostgreSQL. Later versions of PostgreSQL are 64-bit only, which means we cannot use them while continuing to support 32 bit versions of Windows.
Because this is a later version of PostgreSQL than earlier versions of VPOP3 (v3 & 4 use 8.3, v5 & 6 use 9.1, v7 uses 9.5) the VPOP3 installer has to perform a database upgrade.
We recommend having a recent database backup before running the installer to upgrade to VPOP3 7 or later. You could use the most recent daily database backup that VPOP3 usually makes automatically, or you could make a more recent backup manually. This backup is not needed as part of the upgrade process, but it will protect your data in case something goes wrong, so we strongly recommend it. We have tested the upgrade process and it works OK during testing, but we will not be liable for data loss if you do not make a backup and the upgrade process fails for you for some reason, losing data.
When upgrading from VPOP3 v5 or later, this should be a relatively quick process, usually taking no longer than a few minutes. The installer uses the 'pg_upgrade' utility to perform the in-place upgrade, using hard file-links to reduce time taken and the extra disk space needed.
At the end of the pg_upgrade process, the command prompt window will ask you
Does everything above look OK (Y/N)?
Have a quick look back through the pg_upgrade output, and if there are no reports of ERRORS (or FATAL or PANIC errors) then press 'Y' to continue the upgrade process.
If you see any errors, press 'N' instead. the pg_upgrade process will be rolled back and you should be able to continue using the old version of VPOP3. You should then contact email@example.com with details of the problem you had.
When upgrading from VPOP3 v3 or v4, then the pg_upgrade method cannot be used, so the installer has to perform a full database backup & restore, which can take some time, depending on the size of the database.
When upgrading from VPOP3 v3 or v4, you must initially install the 32-bit version of VPOP3 v8 to migrate the data correctly. Once the data has migrated into the database, you can then over-install the 64-bit version if desired.
Whilst VPOP3 v2 did support the use of PostgreSQL to speed up busy systems, this was rarely used.
In all other cases, the upgrade from v2 to v8 should be straightforward because VPOP3 will automatically migrate the data from the old registry & file-based store to the database store. However, you must initially install the 32-bit version of VPOP3 v8 to migrate the data correctly. Once the data has migrated into the database, you can then over-install the 64-bit version if desired.