Disconcerting problem after upgrade to new version

[Evan Burkitt]

I had quite a shock this evening when I checked the balance on one of my accounts and found it had increased by about $2500. The day before I had installed Ubuntu 15.04 on my computer on a new HDD, and copied my gnucash directory from my old drive. My previous GnuCash version is 2.4.10, the new(er) one is 2.6.4.

To cut a long, panicky story short, I discovered that the problem was two transactions from 2007. One was missing entirely and the other too small by a factor of 100: it should have been for 1246.16, it was actually for 12.46. I checked my backups and the same situation exists in a year-old copy; it may go back further than that. Up until yesterday (running from the old HDD) the account balance was correct, and I've reconciled it dozens of times since 2007 with the correct balance.

The only reasonable explanation is that the data have been wrong for a long time, but 2.4.10, at least, is able to tolerate bodged data that 2.6.4 cannot. Has anyone experienced anything similar when moving between versions? Is this worth reporting as a bug?

-evan