Bad rom after making changes with FF3usME 6.7

So my rom becomes "bad" after I make so many changes to it through FF3usME. The game runs fine until the game triggers the first battle in Narshe, then ZSNES crashes. Is there anything in usME that I shouldn't be changing that would cause this? Is it because I'm expanding the rom to 32Mb after I already make changes? (in other words, should I expand a clean rom FIRST before making any changes *at all* in order to prevent this?)

It's kind of hard to narrow down the problem if it's an individual change, because I've made quite a few changes throughout the rom. Any knowledge that anyone may have is much appreciated!

(and for the record, yes, the original rom is 100% clean)

It's most likely a problem with the changes you've made and not the editor, which works fine. Maybe you tried to save without changing anything which can have weird results on the ROM. You can expand your ROM whenever you want, it just add a bunch of FF at the end of the ROM. Have you applied any patch or do event editing?

It definitely seems to be a change I've made somewhere with the editor, but I have no idea what change could have caused it to break the rom. I know I've successfully made changes in the past using FF3usMe, so like you said, it's not the editor. I'm a little bit perplexed as to what I would have done to break it, though.

So you're saying you have not applied any patches at all then? Just to make real sure its not that, since battle crashes are usually always associated with a conflicting (or not applied correctly) patch in my experience.

What does the ROM informations window say there in USME when you open the ROM?

Are you getting any errors upon saving in USME, and/or does anything seem messed up in there, like dialog bytes being -11582521 bytes or any other tell-tale signs of corruption?

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What I would do if you are not able to solve this, is re-insert large chunks of binary data from a backup ROM that still works, little by little until it works again. That way you can hopefully isolate the address the problem is happening in and try and fix it - just make sure to make a backup of the messed up ROM first before doing that...
I would start with copying back whole banks like C2, C3 etc. then narrow it down further. That's just me though, there's probably a less tedious way, but I've saved my ROM by doing this before.

I can't stress enough how important it is to make backups all the time!

ROM internal name: "Final Fantasy 3 "
FF3us, Version: 1.0
Cart size: 32 Mbit
Rom is expanded: yes
Rom is header-less: yes
Patch already applied: Mst sp atk exp., FF3usME mst AI

There aren't any abnormalities throughout the rom in the editor. No weird byte counts, and no saving errors or any sort of errors throughout each tab and part of the editor.

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I seem to have figured out what the problem is. I still get the 'bad rom' error no matter what little change I make to a fresh, clean rom, but that's just ZSNES detecting that the rom isn't fresh... not that it's necessarily an error.

As far as what was causing the battle crashes, it was the Evade bug fix patch. I have ZSNES auto-patching = named .IPS files to my rom, and for whatever reason, it's causing the game to crash on battle enter. I'm not sure what changes I'm making in my rom that's causing it to conflict with the evade bug patch (never had this problem in the past...), unless it requires a headered room. The one I'm editing doesn't have a header.

It does sound like the patch might require a header, yeah.

Oh, and I didn't think you were talking about the ZSNES message there lol, I used to wonder about that also, but figured it was just cause the ROM isn't clean, like you said.

Anyways, glad you figured it out.

Thanks for the help, guys

EDIT: added a header to my patch using one of the header adding/removing tools. Works flawlessly now with the evade IPS. Yay!