[dfe]

Some comment and info with regards to this issue. Exactly the same happened to me.

I did the 3.8.9 upgrade to 4.2.3, everything looked good. The next month I realised all the attachments were gone. The physical attachments were still on the drive, but the filedata table was empty. This to me confirms the problem is in one of the cleanup scripts and not in the actual upgrade script.

Luckily I did a database dump directly after the 4.2.3 upgrade before I started fiddling with any addons or mods. I looked at this db and the filedata table was there with all the attachment entries.

We extracted that one table, updated the refcount field which was zero for all entries to 1, then we imported this one table back into the live system and this brough back all the attachments.

So if there is anybody out there suffering the same problem, you could try a similar process. If you do not have a backup of after the upgrade you will have to run another upgrade on your v3 database. Once the upgrade is completed look at the new filedata table, if the attachment entries are there you need to first update all line items and change refcount from 0 to 1.

Then you need to go back to your live forum and dump all those entries to a sql file just incase.

From the fresh upgrade dump only the filedata table. Now you have to merge this into your existing live system, make sure not to go and delete any new entries that is there.

Hope this helps somebody out there, I lost far too many hours with this after the upgrade.