Before you try this method always try saving with "Save As". Sometimes it works, sometimes it doesn't, but if it does it'll save you a lot of time. When you do try "Save As" always make sure you change the name of the save. I usually just add a number on the end. If it doesn't work here's a solution I found to get around the dreaded "Error 12". I don't know if it will save actual game progress but I DO know it will save any work done on your house. I also know FOR SURE though that it WILL cancel any wishes/promises for your Sims.
This was my situation:
I started a new game, single rich guy, and as usual I built my house from scratch first. I had been saving along the way so I wouldn't have lost a TON of work when the Error 12 came up but enough to be annoying for sure! I hadn't actually played any with the household other than a few second's at the start which is why I can't tell you if it saves progress like skills, relationships, opportunities, etc. I would think it would though.
My solution:
1.) Go into "Edit Town" in the "Options". When it asks if you want to save first click "Just Continue"
2.) In "Edit Town" mode click on the household you are trying to save. Then click "Save Copy To Library". Then click "Household With House". After you have saved it you should see a picture at the bottom of the screen with the family you are using and a little "Folder" icon in the bottom right corner. If you don't see it then try saving a copy again maybe.
3.) Once you know it saved the copy Quit all the way out of the game to the desktop. It would be a good idea at this point to go into your Sims 3 file and COPY your saved game to somewhere else on your computer incase something unexpected happens. That way if something goes wrong you can just reinsert your save "pre edit" back into the save folder so you for sure still have at least what you had saved before the session that gave you the Error 12. Although as far as I know, if you do all these steps you shouldn't have any problems. But... BETTER SAFE THAN SORRY!
I would feel horrible if I caused someone to lose some major advances or worse, their entire game!
4.) Restart the game. Select the last save you made with that household and load it.
**I don't know for sure but I would assume that if you didn't have an actual save yet you should be able to start a new game in the same city (possibly even a different one!) and still be able to do this. If you can and you do this process then skip steps 5 and 6.**
5.) Once loaded go into "Edit Town" again. Again selecting "Just Continue".
6.) Select the "Bulldoze" tool and click the house you are in that you were trying to save before the Error 12. Bulldoze it. *Important* BE SURE TO ONLY BULLDOZE IT ONE TIME AS YOU CAN ACTUALLY DELETE THE LOT ITSELF!
7.) Once the lot is empty select the Copy you saved after the Error and click "Place Copy". Place it on the lot you were using (or any other lot it will let you if you want!).
8.) (I'm going off memory on the actual wording here) Click "Choose Household" and select the house you just placed. It will tell you that you can either play now or continue looking around or whatever. Just click the "->" arrow at the bottom of that message and WAALAA! You are back to your game without loosing your progress from the error!
Like I said, I don't know if it will save all progress or just your building progress but I would think it is saving an exact replica of the current household, skills, relationships and all! (Minus the sims wishes though, but hey, better than loosing EVERYTHING)
If I come across the situation again after I've been actually playing the family and I find out for sure about saving actual progress of the Sims themselves I will come back and post it.
As far as what DianaAK had posted, that most likely has something more to do with your system I think. I KNOW for sure that it's not clicking and lagging that causes it, or at least it's not the ONLY thing that can cause it because when it happened to me I had not done much of anything. I placed a small pool with slides, diving boards and ladders, wallpapered a few rooms and changed the color of the wood floor on my porch. That was about it. Although the game had been on for at least 3 or 4 hours for that session because I was doing other stuff and coming back to it now and then. I think, if anything, that it's more about the length of time the game has been running.
Like Swede said, RESTART YOUR GAME ON A REGULAR BASIS! Personally I do about once every hour of game play (real time not Sim time! LOL)
I REALLY hope this helps people and works for you!
***Please reply on here or email me and let me know if this has helped any of you! It took me about an hour to retrace the steps I did and to type this all up and if it helps anyone it will be TOTALLY WORTH IT and I will be much more willing to take the time to respond to other things in the future!***
I know how SUPER FRUSTRATING it is to lose a ton of progress! Now if they'd only make a way that you could save your progress with your sims while you are actually creating them that would be FANTASTIC! Twice last week I was creating a household and it crashed *right* before I was done. Between the 2 times I lost over 7 hours of progress! AARRRRGGGHHHH!!!
