I'm hoping someone can help me with this. Everything was perfectly normal until earlier tonight when I was editing some sims in SimPE. When I tried to open a sim, the program threw an error, so I closed it. Then I tried to run HoodChecker to make sure there wasn't corruption. But it won't even run, a message pops up that indicates that sim description instance 617 is corrupted. I've never seen this before, and I'm really upset thinking I did something to mess up my hood. I'm able to open up the neighborhood in SimPE, but as soon as I try to use the sim searching tool I get an error message. Both HoodChecker and SimPE have no issues when I try one of the other neighborhoods in my game.

I haven't tried to open up the neighborhood in game since this happened. I'm not sure if there's anything I can do to fix this. I don't have any kind of recent backup of the neighborhood (only one from like six months ago). I can restore to the old backup if necessary, but beforehand I just want to see if this damage is reparable.

It is a good thing you caught the problem before you opened the 'hood in the game. The game will either crash when it tries to read the sim's file or it will remove the sim from the game which has the potential to corrupt the whole 'hood. Hood checker uses dlls from SimPE so if one has a problem then so too will the other.

When SimPE corrupts a file that way it's utterly corrupt and the only way to fix it is to replace the file.
Can you work out which character file it is and if so does that sim exist in your old backup? You may get away with just replacing the one character file from your old backup. That may require aging the sim up and down in game if in the old file the sim is a younger age.
The alternative is to make a new character file but that requires finding out the sim's GUID which would have to be gleaned from the neighbourhood file so it may not be so simple when SimPE falls over every time it tries to read the sim's file.

If all else fails if you can 'zip' up the hood and upload it somewhere I'll take a look at it for you.

Thank you so much for your help!

The corrupted sim is one of the ones I created and added to the game just yesterday. I had added in a whole batch and was just starting to edit their personalities in SimPE. I guess I've learned the hard way that I need to backup before using SimPE every time. Based on when the character file was edited (there's only one that's later than the time I closed the game), I think I can narrow it down to one character file.

I can get into the neighborhood in SimPE, but when I try to use the sim browser tool the error messages pop up. Is there any way besides that tool that I can locate the sim's GUID?

That's very kind of you to offer to look into the neighborhood for me! Only if you have time, I don't want to inconvenience you too much. I've never uploaded an entire neighborhood before, how would I do that?

Try moving the corrupt character file out of the characters folder before starting SimPE to prevent the error.
If you select the sim's family it'll list the first names and GUIDs of the family members, if you've removed the character file the one you want will be 'Unknown'. Write down that GUID somewhere.

Create a temporary 'throw away' 'hood and create a new sim similar to the one that's damaged. Exit the game, locate that character file and rename the file to match the damaged one. Open it in SimPE and in the Object Data change both the GUID and the Fallback GUID (not the Orig. GUID as that must point to the sim template) to the one you wrote down. Replacing the damaged file with that one should work.

The lesson here is if SimPE throws an error never continue and try to save the file you are working on, just exit SimPE and start again.

It might be messed up worse than I thought. I tried removing the character file I thought was the culprit, but SimPE still gives error messages. Then I tried removing all the files for the sims I created that day, but even then the error messages persist. After that, I removed every file that was edited the last day I played, and I still got the error message. I have no clue at this point which file or, more likely, files are messing things up.

Thank you so much for your help! It's seeming like my neighborhood may be beyond repair, but at least I'll be more careful in the future to prevent this kind of thing happening again.

How difficult it'd be to retain enthusiasm for a 'hood that's been 'rolled back' six months, it'd be a damn shame if we can't fix this. SimPE is not going to corrupt multiple files at once, only the file you are actually working on. While you are working on a file any other file SimPE opens to get information from are opened in a read only form. This seems more like faults in the neighbourhood file.

Hmm, how could I go about figuring out where the corrupted neighborhood file is?

I'm trying to remember exactly when the error messages started in SimPE. First I got a weird message about it not being able to connect to the internet, which I'd never seen before and didn't get because I didn't think SimPE needed the internet. I don't know if I pressed something by accident? Then I continued editing the sim's personality I was working on. At some point I got a "would you like to save changes you made" message, and thought I must have forgotten to hit commit and then save like usual, so I clicked yes. Maybe that did something weird. I think after that when I tried to edit another sim I started getting error messages. After that I shut it down and tried unsuccessfully to run HoodChecker.

The primary neighbourhood file is the one in the neighbourhood folder named xxxx_Neighborhood.package where xxxx is the prefix for that neighbourhood, for example Pleasant View's is N001_Neighborhood.package. If you use HoodChecker regularly you may have a very recent backup, HoodChecker creates a backup of the neighbourhood file before making changes which will be a file with the same name but a .bkp extension.

The backup in there is from January. I guess I hadn't run HoodChecker in a while. There were some months when I didn't have much time to play so I'm not sure exactly how much progress I've lost. Is there anything I can do at this point to try to fix the neighborhood or should I use the backup?

I'd suggest you try playing it before replacing it with your backup, it may crash, freeze up or lose some sims but since the game is more robust than SimPE it may actually work. At this stage you have nothing more to lose by trying.
I have no idea if it is the neighbourhood file or several character files that are damaged. If you can 'zip' it up and upload it to a file sharing site before playing it I'll gladly take a look at it for you.