VPOP3 v9 and later requires a 64 bit version of Windows 8.1 or later

VPOP3 v9.x uses PostgreSQL 18 as its database engine. This can only easily be upgraded from PostgreSQL 9.3 or later, which means it must be an upgrade of VPOP3 v7 or later. If you are using an earlier version of VPOP3, then upgrade it to v8.7 first, then upgrade to v9 or later

If you were previously using a version of VPOP3 earlier than v5, you must install a 32 bit version of v8.7 first, and let it migrate all the data into the database before upgrading to a 64 bit version of VPOP3

Because PostgreSQL 18 is a later version than PostgreSQL used in earlier versions of VPOP3, the installer has to perform a database upgrade.

We recommend having a recent database backup before running the installer to upgrade to VPOP3 9 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 v7 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 support@pscs.co.uk with details of the problem you had.