So I fired up D2 again

[dave in the basement]

I found a Windforce and a Gul rune last night! Down to 40 items left to find.

Congrats on the Windforce! That's one of the items that always eluded me in my self-found grail. The glorious golden hydra bow!

[mn4nu]

Found an Azurewrath last night! This one is sweet since I found about 9 Lightsabers prior to getting the good phase blade. 38 items to go!

[Timinator]

Woohoo go Jeff! And one pinky can’t drop. It’s coming up 13 years since my first wind force but still a special time when you get a new 87

[Darkness]

Had a really nice large charm drop last night. +157poison damage over 6 secs with an added 6% gold drop. I'll be holding onto that one for future use.

[mn4nu]

Nice charm Darkness! The best one those I've found so far in PlugY is 313 damage/11 sec small charm. It's rare to get 2 good poison damage mods on a charm.

I found a unique Kraken Shell last night, so 37 items to go.

[Darkness]

I've had some "generic bad file" weirdness.

So I've decided to progress from 1.09 to 1.13d. Fine. Upgrade the files, launch my Barb and I get the generic bad file message. Perplexed I try that with some of my mules. They're fine. I try it with the mule I've been using to transfer items to my 1.14 characters. Same message.

Revert all files (plus saves) back to 1.09, take items off mule. Try again. Same message. Revert back again.
Try character files, both mule and barb in 1.14, they work fine.

Try back in 1.09 again. Both characters work fine.
Try 1.13. This time the mule is fine but the barb is not.
Mule all items on the barb over to another mule for the express purpose of testing where the corruption is.
Barb loads fine. Mule does not. Aha, I think, item on the mule is corrupt.
Start moving the items, one by one, over to the another toon, to test which is the corrupt item that means the characters won't load.
Every item loads fine.
Move all items back to the Barb, the character loads fine.

I have no fucking clue what the problem was.