If you try to bcp data into the syslogins system table from an earlier version of the server, bcp will fail. This is because in 12.0 and 12.5, two additional columns were added to syslogins. If you need to bcp into syslogins, you can work around the problem by creating a dummy table to hold the data, altering the table to add two columns, and then copying the data into the 12.5 syslogins.
This issue could occur with other system tables that have added columns. You might encounter the problem first with syslogins if you need to copy this data as part of the upgrade.
See What’s New in Adaptive Server Enterprise for changes to system tables in ASE 12.0 and 12.5.