Game guide:Avoiding corruption


 * This tutorial is for The Sims 2 only.



Corruption in The Sims 2 is when some or all of the game data, whether it is in a neighborhood or in the core game files, become corrupted. Corrupted game data is a bad thing, and could make a neighborhood or the entire game unplayable, depending on what type of corruption occurred. This game guide will try to clear up the misconception between game corruption and neighborhood (shortened to 'hood') corruption, highlight known actions that guarantee corruption, and provide solutions to fix existing corruption.

The difference between game corruption and hood corruption
It's common for players to mix up game corruption and hood corruption, and some think all corruption requires a full reinstall.

To clear this misconception up, it's important to know that the game stores information on your computer in TWO different locations, assuming that you installed the game in the default locations.

The C:\Program Files\EA GAMES location is where the files that make up the core and backbone of the game are housed. These include the objects.package file, the Sims3D files, audio files, movie files, default items in the game, user interface, graphics, and the game's programming. It also contains the character files for Universal NPCs, such as the Grim Reaper, Mrs. CrumpleBottom, and the Therapist. The files here are normally never modified, and shouldn't be modified (Mods/hacks do modify the game's programming, however, it doesn't actually modify the files themselves. The mod loads after the original files, so code from the original files is simply not used, and code that the mod modifies is used instead). There are a few files here that can safely be modified should the player know exactly what they are doing. Corruption that occurs here is known as "Game Corruption".

The player's saved game data, custom content, lot & houses bin, storytelling images, neighborhood stories, etc. are stored at C:\Users\ \My Documents\EA Games\The Sims 2\ or C:\Documents and Settings\ \My Documents\EA Games\The Sims 2\, depending on the version of Windows installed on your computer. Corruption normally occurs in a neighborhood's folder, located in the Neighborhoods folder. Each neighborhood gets a folder with a unique ID on it (E.g. 'N001') where data relating to the neighborhood, such as Sims, relationships, memories, and lots in the neighborhood are located. Corruption that occurs here is known as "Neighborhood Corruption", and fortunately, it is far less serious than game corruption, but it's also far more common.

Known symptoms of corruption
This is an incomplete list of possible symptoms that may indicate corruption. Not all symptoms listed here may be a sign of corruption, but may be indicators of other problems, such as bad custom content.

Symptoms include:
 * Children and toddlers with long-term wants other than Grow Up.
 * Wants that don't fit the age group (e.g. a toddler who suddenly wants to go on a date).
 * Memories and thought bubbles that contain squiggly lines or stretched or distorted text.
 * Memories being lost or totally random.
 * Disappearing Sims.
 * Disappearing lots.
 * Sims losing family members in their family tree.
 * Sims becoming unplayable.
 * Lots becoming unplayable.
 * Buy and Build Mode becoming indefinitely disabled.
 * "The Sims 2 has stopped working" appears

When a neighborhood or game becomes irreversibly corrupted, it is referred to by some players as a "BFBVFS" ( B ig F iery B all V isible F rom S pace).

Avoiding game corruption
The following actions are known to corrupt your game files. They should never be attempted, unless you are just happy to have a broken game. Actions taken here will not only corrupt your game, but will also corrupt all your neighborhoods, existing and future. In short: Do not try this at all!
 * Interact with universal NPCs, such as the Grim Reaper, Mrs. CrumpleBottom, Therapist, Pollination Technicians, ideal plantsim, etc. in any way outside of their in-game designated purposes.
 * These Sims do not have playable character data. Their character files are not located in the folder of the neighborhoods, but in the objects.package file in the C:\Program Files location. Modifying them in any way or form that involves hacks, cheats, or SimPE will corrupt that file.
 * Here is an incomplete list of known NPCs that are safe to play as, and those that aren't.
 * Modify any file in the C:\Program Files location in any way or form.
 * These files were not intended by Maxis/EA for you to tamper with them, and doing so could void your warranty and destroy your game. There are a few files that can be safely modified if you know exactly what you are doing. The allmenus cheat is a perfect example of safely modifying the core game files.

Avoiding neighborhood corruption
The following actions will permanently corrupt your neighborhood. There are methods of getting a corrupted neighborhood to keep running for a good while longer, but these are not permanent solutions. The best option is to never attempt these actions.
 * Delete a Sim in the family bin.
 * As crazy as it seems, but EAxis didn't code this part properly, and now it's costing a lot of people their beloved neighborhoods. The in-game delete button doesn't delete the Sim entirely. It shreds off a portion of the Sim's character file and their Sim Description (which is located in the Neighborhoods.package file), unlinks the character file, and leaves a 1KB character file in the "Characters" folder. The game does not properly clean out all references to the Sim, which means that memories, gossip, relationships, Sim Wants and Fears, etc. that involve the deleted Sim are now corrupted, as they point to non-existent data. Even if a Sim was created fresh out of Create-A-Sim, it doesn't mean that they are safe to delete via this method.
 * This page shows you how to delete a Sim correctly. It's not perfect, and it still leaves some rubble behind, but it is nonetheless safer than the in-game delete button.
 * Delete Character Files from the C:\Documents\EA Games\The Sims 2\Neighborhoods\\Characters folder.
 * The neighborhood saves Sim data in two different locations - the Neighborhood.package file, and the character file itself. If you delete the character file without properly cleaning the Neighborhood.package file, your hood will be left with half-a-Sim, and will not function properly.
 * The character file(s) can be deleted safely once this method is followed.
 * Delete Lot Files from the C:\Documents\EA Games\The Sims 2\Neighborhoods\\Lots folder.
 * The neighborhood saves lot data in two different locations - the Neighborhood.package file, and the lot file itself. If you delete the lot file without properly cleaning the Neighborhood.package file, your hood will be left with half-a-lot, and will not function properly.
 * To delete a lot, move all Sims, tombstones, and urns out of it, sell the lot if it is an owned business, use Cyjon's Lot Inspector to verify that it is safe to delete, and then bulldoze it from the neighborhood.
 * Move an occupied lot or an owned community lot to the lot bin.
 * The game transfers character data from the neighborhood to the lot bin, but does not completely erase all traces of the Sims from the neighborhood. Sims in the neighborhood may gossip about the missing Sims, spreading the corruption around the hood. Also, moving the lot back into the neighborhood will create new character files, instead of overwriting the existing ones. Moving the lot into another neighborhood will introduce the corruption to the hood it is moved into.
 * You can move Sims from one hood to another by extracting their appearances and then recreating them in Create a Sim in the new neighborhood. This is the only known method that is 100% safe.
 * Occupied lots that are already in the bin are safe to delete, as the damage has already been done.
 * Move a previously occupied/owned lot to the lot bin.
 * Lots that can be lived in or owned by Sims will carry references and tokens that are connected to the Sims that live on/own the lot. If you move the lot into the lot bin, those references go along with it, and will corrupt any neighborhood that it is moved into.
 * Install an occupied lot, including downloaded lots that ship with families.
 * If the sims had any relationships with any sims not living on the same lot in their original neighborhood, placing the lot in your neighborhood will create partial character files of all the sims that the lot's residents used to know. This will cause errors in the long run. You may find some occupied lots available for download which the creator has 'cleaned' to make them safe; the cleaning process is not 100% reliable, so you should exercise extreme caution and back up your neighborhoods before installing. The two occupied lots, Kat and Kim, that ship with Pets, are 100% safe.
 * If you want the Sims that come with the lot and not the lot itself, create a new neighborhood, move the occupied lot into the neighborhood, and then extract the appearances of the Sims using this method. Then re-create the Sims in CAS in the neighborhood you want to move them in. You can delete the corrupted neighborhood if you wish, as you no longer need it.
 * Use the DeleteAllCharacters cheat.
 * This cheat, like the family bin delete button, will destroy part of all the character files in the neighborhood and leaves lots of junk, orphaned information. New Sims created may acquire this corrupted data.
 * If you want to create a neighborhood with no Sims at all, follow these instructions.
 * Delete Tombstones/Urns
 * Tombstones and urns are treated as Sims by the game. Deleting a tombstone/urn is the same as deleting a Sim using the in-game delete button - the character file is damaged, the Sim unlinked, and the memories, gossip, and references left behind to corrupt the neighborhood.
 * Install Pescado's No Unlink on Delete mod now to avoid corruption caused by the deletion of urns/tombstones. The mod prevents the game from shredding character file data when urns/stones are deleted. As long as the character data is intact, and nothing is unlinked, the references to the Sim are valid and uncorrupted, because they are pointing to a Sim that exists.
 * Again, to delete Sims, follow this method.
 * If you wish to remove the urns/stones because of the annoying ghosts, create a community lot designated as a cemetery lot, and move the graves over there. Graves there will appear by the pay phone.
 * Graves in apartment lots are extremely unstable. If the last Sim in an apartment slot dies, the grave will be moved to a random community lot, but it may also be deleted or moved to a non-existent lot. Use the Select Your Cemetery mod to force the game to give you the option to move the urns to a community lot.
 * Move lots that have graves to the lot bin.
 * Exactly like moving occupied lots in the lot bin. Graves are treated as Sims by the game, and moving them to the lot bin will leave corrupted references behind. Moving them back into the neighborhood or into another neighborhood will simply cause more corruption.
 * Allow a Sim to die with graves in their inventory.
 * When a Sim dies, all items in their inventory are deleted. Deleting graves, as mentioned previously, will damage the dead Sim's character data, and corruption will spread around the neighborhood.
 * Resurrect pre-made dead Sims that ship with the game.
 * Most of these Sims have incomplete character data, and will cause corruption if resurrected.
 * Put tombstones or urns on any of the Open for Business display cabinets or shelves.
 * When a tombstone or urn is placed on an OFB shelf, it will be duplicated. The duplicate tombstone will still be connected to the sim. This will corrupt the Sim.
 * Have too many Sims in your neighborhood.
 * The game actually has a character file limit. If you have the base game or the University expansion, each neighborhood has a maximum population limit of 1000 character files. If you have Nightlife or a later EP/SP, the limit has been increased to around 32767 files.  Once a neighborhood has reached the limit, any new Sims created will immediately be lost, and other symptoms of corruption may present themselves.
 * Deleting a Sim using this method will remove the character file from your neighborhood, which can help in preventing you from reaching the limit.
 * The best way to avoid hitting the limit is to not generate so many Sims in the first place. Several mods can help prevent excessive Sims from being generated.
 * NoTownieRegen, prevents the game from generating new townies.
 * Anti-Redundancy, prevents the game from generating more than 1 of each NPC type, instead of the standard 3 NPCs per NPC type per neighborhood.
 * NoSSrespawn, prevents the game from generating new secret society members.
 * NoDormieRespawns, prevents the game from generating new dormies.
 * NoStrayRespawn, prevents the game from generating new strays.
 * CJ-TownieApartmentResidents, allows the game to pick regular townies as apartment neighbors and roommates instead of social class townies, eliminating the need of generating them.
 * CJ-ThereCanOnlyBeOneProfessor, forces the game to only generate one professor instead of two per major.
 * You can also create a new neighborhood with no Sims at all in it.
 * Save with ghosts active on the lot.
 * If you load a lot with ghosts active, the game may delete all the graves on the lot. This may be to do with the fact that the ghosts are literally physical manifestations of the 'Grave-Sims' (as the game considers graves as Sims) and so the game removes the tombstones so that it isn't saved with two physical manifestations of the same Sim, which is usually not possible. When the graves disappear, the character file they are linked to gets partially deleted, leaving behind floating and orphaned references to the Sim, and so corruption occurs.
 * Pescado's No Unlink on Delete mod may prevent corruption from occurring if this happens.
 * Remove multi-Pollination Technician or multi-PlantSim mods
 * Multi-PT and Multi-PlantSim mods consist of one controller package which tells the game to use the custom PTs/PlantSims, and a number of packages which are the new pollination technicians or PlantSims themselves. Whenever you play a neighborhood with a multi-PT/PlantSim mod installed, the characters (namely the Sim Description) are added to that neighborhood even if none of your Sims are abducted or turned into PlantSims. If you delete the PT or PlantSim files from your Downloads folder, you are basically deleting their character file without properly cleaning the Neighborhood.package file, which will corrupt your neighborhood.
 * If you want to change to a different multi-PT or PlantSim mod, remove the controller package (usually the smallest one), but leave the character packages in your Downloads folder.
 * If you're starting a new neighborhood and don't want the PTs or PlantSims to be added to that neighborhood, copy the PT and PlantSim character files from your Downloads folder into the Documents\The Sims 2\Neighborhoods\Nxxx\Characters folder of each of your existing neighborhoods, then delete them from your Downloads folder.
 * You can also avoid this issue altogether by adding the files directly to the Characters folder of the neighborhoods you want the custom NPCs to appear in, rather than putting them in the Downloads folder.
 * Save with Sims on the telephone.
 * When Sims chat with other Sims on the phone, the other Sim is, technically, considered to be on the lot, even though they are nowhere in sight. These Sims are called "Off-World Loiterers". If you save the lot, and install a new hack, patch, expansion pack, or stuff pack, all the objects on the lot will be reset. This normally isn't a problem, except when there are off-world loiterers that aren't a member of the household. The Sim making the call will be reset and return to normal, but the Off-world Loiterer is not sent home properly, which will cause problems in the long run.
 * Pescado's FFS Lot Debugger has an option to remove off-world loiterers, but it only appears when they are present. Do not remove off-world loiterers while they are interacting with the Sim on the phone, as that will cause problems.
 * Move lots to the lot bin with off-world loiterers on them.
 * As previously mentioned, it is unsafe to move occupied lots into the lot bin. It is also unsafe to move a family out while one of its members are on the phone. The off-world loiterer is then left behind, and will remain even when another family moves in. Moving the lot to the lot bin will carry that Sim along with it, and will cause problems over time.
 * Pescado's FFS Lot Debugger has an option to remove off-world loiterers, but it only appears when they are present.
 * Cyjon's Lot Inspector can tell you whether it is safe to bin or delete the lot. It can also locate off-world loiterers on unoccupied lots.
 * Attempt to move in, make selectable, or modify certain NPCs outside of their in-game designated purpose.
 * There are certain NPCs that have playable character data and are possible to move in without the use of cheats - those Sims are usually safe, and probably intended by EAxis for you to move them in. However, there are some Sims that do not have a complete character file, such as the Social Worker or Repo-man. Tampering with them in any way or form outside of the in-game designated purposes may corrupt the neighborhood they are in.
 * The Social Worker is glitchy, as she may be spawned as a blind date through the Gypsy Matchmaker. Do NOT attempt to interact with her if she does - delete her using the moveobjects cheat immediately.
 * This incomplete list indicates which NPCs are safe to play as and which ones aren't.
 * Rezone a lot with Sims living or staying on it.
 * The game has different rules for different types of lots. Some lot types do not allow the lot to be saved, others could make the lot disappear from the neighborhood. Only perform such a task on empty, preferably new & unused lots.
 * Remove custom careers/majors while a Sim is employed or enrolled in them
 * This will corrupt the households of the sims who use them. Your household may not load, and could cause problems when the sim visits your other lots. Be sure to get all Sims employed/enrolled in that career/major to quit, and then remove it.

Avoiding fixable neighborhood corruption
The corruption here is known to be fixable, but it still should not be attempted. It's always best to avoid corruption than to get corruption and struggle to repair it.
 * Delete custom or geneticized/townified skins or eyes
 * This will cause all Sims who were using the deleted skin or eyes to have corrupt DNA. You will have to fix the DNA of all affected Sims individually in SimPE.
 * Instructions on how to fix the genetics are listed here (login required) or here (no login required).
 * Deleting default replacements is safe.
 * Delete custom foods
 * This breaks want trees for Sims whose favorite food was the deleted food, and will corrupt the memories of Sims who have a "Learned to make" memory for that food.
 * Use Pescado's Lot Debugger to reset all Sims whose favorite food was the deleted food.
 * Use SimPE to remove all memories, gossip, and references to the deleted food. This, however, is very time-consuming, and you will no doubt miss something.
 * It may be possible to avoid this problem by editing the food so that it is set to false for all mealtimes. This will hide the food in-game but will not cause memory corruption.
 * Let Samantha Ottomas and/or Sarah Crittur's pregnancies come to term.
 * A glitch exists in the game that causes pregnant Sims shipped in the family bin to carry babies with incomplete character data. Both Samantha Ottomas and Sarah Crittur suffer from this glitch. The Seasons patch fixed this problem in both Samantha and Sarah. However, it only fixes instances of these families in neighborhoods first opened after the patch is installed, including neighborhoods that shipped with Seasons or later expansion packs but that were not opened until after the patch was applied. Instances of the family in neighborhoods that were opened before the patch was applied will have the corrupted families.
 * If you have the unpatched Ottomas/Crittur family, and Samantha/Sarah has not yet given birth, use the InSIMenator or Sim Manipulator to terminate the pregnancy.
 * If Samantha/Sarah has already given birth to the babies, check their family tree with SimPE. If the babies recognize Peter/Danny as their father, you are safe. If they recognize someone else, such as a townie, another playable Sim, or a pet, change the family ties to the correct father. However, this is not a permanent solution, and your neighborhood is already corrupted.

Game corruption
Fixing game corruption is actually quite simple, but it can be time consuming. It's easy to simply check whether a file is corrupted or not - simply mouse-over the files and check the date it was modified at. The files should've been last modified in 2008 and earlier. If they were modified after that, it's possible that they're corrupted.

The easy way
The easiest way to fix game corruption is to reinstall the entire game! Back up your saved games and custom content, then proceed to uninstall all expansion packs, stuff packs, and the base game. Then, install everything again. Copy your back up and move it back into the My Documents\EA Games\The Sims 2 folder. Install all the patches and make your game files read-only, if you haven't already (instructions are listed further down the article).

The hard way
First, you'll need to locate the corrupted files. Commonly corrupted files include the objects.package file, the files in the Sims3D folder, and lights.package.

Fortunately, a clean, uncorrupted copy of the files are located on the game CDs/DVDs. You can easily replace them without the hassle of reinstalling the game.

First, plop the game CD/DVD (the one you use to start the game with) into the CD/DVD drive of your computer. The following is a list of what CD/DVD you need to use.


 * Base game - CD #2 (or DVD if you have the DVD version)
 * University - CD #1
 * Nightlife - CD #2
 * Open For Business - CD #1 (the only CD)
 * Family Fun Stuff - CD #1 (the only CD)
 * Glamour Life Stuff - CD #1 (the only CD)
 * Pets - CD #1 (or DVD if you have the DVD version)
 * Seasons - CD #1 (the only CD, or DVD if you have the DVD version)
 * Celebration Stuff - CD #1 (the only CD, or DVD if you have the DVD version)
 * H&M Stuff - CD #1 (the only CD, or DVD if you have the DVD version)
 * Bon Voyage - CD #1 (the only CD, or DVD if you have the DVD version)
 * Teen Style Stuff - CD #1 (the only CD, or DVD if you have the DVD version)
 * Freetime - CD #1 (the only CD, or DVD if you have the DVD version)
 * Kitchen And Bath Stuff - CD #1 (the only CD, or DVD if you have the DVD version)
 * IKEA Home Stuff - CD #1 (the only CD, or DVD if you have the DVD version)
 * Apartment Life - DVD #1 (the only DVD)


 * The Sims 2 Deluxe - DVD #1 (the only DVD)
 * The Sims 2 Double Deluxe - DVD #1 (the only DVD)

Then, go to "My Computer/Computer", right-click on the CD/DVD, and select "Explore". If autoplay starts up, close it.

There should be a file called "compressed.zip". Open it, and there should be a folder called "Res" in it. Open it, and you'll see it looks a lot like the C:\Program Files location. Find the file that you wish to replace, for example, the objects.package file. Right-click and Copy the file.

The Sims 2 Deluxe: The installation files are not stored in a compressed file, but instead in uncompressed format within folders called 'Base' and 'EP2'. The game executables are stored in Compressed.zip, however. You can just copy and paste any files that are not in the compressed file.

The Sims 2 Double Deluxe: The installation files are not stored in a compressed file, but instead in uncompressed format within folders called 'Base', 'EP2' and 'SP4'. The game executables are stored in Compressed.zip, however. You can just copy and paste any files that are not in the compressed file.

Now go to C:\Program Files\EA Games\The Sims 2 + the EP/SP that you use to start the game with\TSData\Res\The folder where the corrupted file is. Right-click on the corrupted file, and hold Shift while clicking Delete. This will delete the file right on the spot, instead of the hassle of sending it to the Recycle Bin. Now right-click and "Paste" the fresh file into the folder. Apply the patches again, and you're good to go!

Note: If multiple files are corrupted, or if you're not sure what files are broken, you can just Shift+Delete the entire "Res" folder and replace it with the "Res" folder from the game CD/DVD. As always, you must re-apply the patches, as the files on the CD/DVD are not patched.

Hood Corruption
The only way that will completely remove hood corruption is to delete the entire neighborhood. You can either delete the hood in-game at the main menu, or by deleting the folder in My Documents\EA Games\The Sims 2\Neighborhoods\.

If it was a pre-made hood, you can reset it to the default state using this method. Be sure to delete the old, corrupted neighborhood before placing the new one in, otherwise you'll just corrupt it further.

The methods listed below can help reduce the risk of corruption, as well as provide options to fix it. Remember that most corruption is permanent - your neighborhood is essentially living on borrowed time. If you've become attached to the Sims in your hood, extract their appearances so you can re-create them in CAS in your new neighborhood once the old dies.

Suggested methods to reduce/prevent/fix corruption
The best thing you can do to prevent corruption is to avoid doing the actions listed above, and follow the advice given. There are a number of mods and programs, created by skilled modders, that can help reduce corruption.
 * Pescado's No Unlink on Delete mod.
 * This mod prevents the game from destroying the character data of graves that are deleted for any reason. It will NOT fix instances of graves that are deleted before the mod was installed.
 * Pescado's FFS Lot Debugger (AKA The "Batbox").
 * This is a buyable object found in the Miscellaneous/Miscellaneous section in Buy mode. It provides a number of options to fix problems that can occur with lots, delete stuck objects/tiles, and remove gossip. It also has the options necessary to delete Sims the correct way.
 * A list of its functions can be found here.
 * Arek_91's Select Your Cemetery mod.
 * This mod allows you to select where you want to move graves from a lot to the community lot of your choice, instead of having the game strap a rocket to it and launch it into space. You can also choose to keep the graves on the lot like normal, if you wish. This is absolutely crucial for players with Apartment Life.
 * Mootilda's Hood Checker.
 * This nifty little program will scan your neighborhood for any unusual or corrupted references, and provides an option to remove/fix them. It can detect and fix Family Ties, Sim Relations (SREL), Sims Wants and Fears (SWAF), and Memories. It will also scan for missing character file data, misplaced graves, and other items of interest.
 * Mootilda's Sims2Pack Clean Installer.
 * This program is intended as a replacement to the game's default Bodyshop Installer. It allows players to properly install .sims2pack files, and allows to clean out any mods, hacks, or custom content that may have latched on during the packaging process. It can also show you whether the lot is occupied or not, so you can avoid corrupting your hood without knowing what happened until it was too late.
 * Cyjon's Lot Debugger.
 * This is designed to compliment Pescado's FFS Lot Debugger. It provides some options for fixing bugs, as well as report on some very useful information.
 * Cyjon's Lot Inspector.
 * This object is buyable from the Miscellaneous/Miscellaneous section of Buy mode, and will report on whether the lot is safe to bin or delete.
 * NOTE: Users who do not have Apartment Life or Mansion & Garden may find that the object doesn't work correctly for them. To make it work, press "Ctrl+Shift+C" to open the cheat box, type in boolProp testingcheatsenabled true, and click on the Lot Inspector. An object error dialog with "Bad gosub tree number" should pop up - click on "Cancel" to ignore the error. The inspector should then file a report.
 * Pescado's Anti-Redundancy mod.
 * This mod prevents the game from generating more NPCs than needed, such as preventing multiple Unsavory Charlatans or Tour Guides from spawning. Instead, the game will call upon existing NPCs, only creating more when those are unavailable. This can prevent character file overload caused by the game generating loads and loads of NPCs.
 * Cyjon's There can only be one (Professor) mod.
 * This mod only allows the game to generate one professor for each major, instead of the usual two. This can reduce the amount of character files in the neighborhood. Not required if you do not have University.
 * Pescado's Creature Fixes mod.
 * This mod, in addition to fixing a number of bugs, prevents vampires from biting Mrs. CrumpleBottom and any other NPCs, which can prevent both unwanted and unstoppable neighborhood and game corruption.
 * Pescado's No Corrupted Death Memory mod
 * This mod prevents the formation of "corrupted death memories", seen in the form of "jagged lines", "tombstone", or "dead Sim". Will not remove existing memories.
 * Back up your saved games.
 * All players are strongly recommended that they back up their saved data regularly. Players that either corrupt their neighborhood or notice an unusual problem that doesn't appear to be caused by bad custom content can simply revert to an earlier version of their neighborhood, similar to System Restore.
 * Backing up won't prevent corruption from occurring - it just allows you to revert to an uncorrupted version of your neighborhood should the original become corrupt. If your earliest backup is corrupted, you will have nothing to revert to.
 * This method does not prevent game corruption.
 * Tarlia's Fixed Templates.


 * It's worth noting that pre-made neighborhoods ship pre-corrupted. Strangetown is the worst of all. These templates have fixed most of the corruption in the hoods.
 * Download and install all the official patches.
 * EAxis has released patches for the game that fix many problems with the game. All players should install the patch, regardless of what expansion packs they have.
 * Make all game files read-only.
 * Making the game files read-only prevents the game from writing to those files, preventing game corruption from ever occurring. It will NOT fix existing corruption, however.

To make the game files read-only, go to C:\Program Files\EA Games\. Select ALL of the folders in there, right-click and select "Properties". Click on the "Read-only" box twice, so it's checked instead of just shaded. Select "OK". Your computer will then proceed to make all the files read-only. Remember to apply all the patches before doing this - if you need to install a patch after doing this method, you'll need to unset the read-only flag for all the files before you can install the patch. Also, if you hope to enable the allmenus cheat, you'll need to unset the read-only flag from the file you want to edit.

This method does not mean you can attempt to move in Universal NPCs or tamper with them in any way or form - it is only as a safeguard to prevent the game from possibly corrupting its own files.

Do NOT make the files in the C:\My Documents\EA Games\The Sims 2\ location read-only. The game needs to modify those files in order to save your game. If you make them read-only, your game may not function correctly. Certain files, such as custom content, extracted appearances of Sims, Camera.txt files can be made read-only safely, but there's no point in doing so.

Misconceptions regarding corruption
Over the years, a number of misconceptions emerged when corruption was first revealed to be extremely common in the game. At the start of this article, one of the biggest misconceptions was debunked - game corruption and neighborhood corruption are two different things. This list contains some common misconceptions regarding corruption.
 * Leaving testingcheatsenabled on for long or extended periods of time will cause corruption/game crashes/other horrible very bad things.
 * The cheat itself doesn't cause corruption - it's the options that the cheat provides that can destroy your entire game. Things like the Tombstone of Life and Death, which are spawnable via testingcheatsenabled, will cause corruption if used to move in/make selectable universal or known problematic NPCs. Also, the "Force Error" option that appears when shift+clicking an object will not cause corruption if clicked, but it's recommended that you do not use the option recklessly, as it's primarily used to resolve issues.
 * Object Error dialogs
 * Just because you see an error dialog does not always mean something is dangerously broken! Instead, you should be grateful that the software is aware that there is a problem and notified you, as if it did not have this functionality, it would simply crash. Object error dialogs are popped up by the game when an object in the game encounters a problem and is unable to continue. The dialog provides you with the name of the object that encountered the error, what the error was, and where the error log was created and dumped on your computer, as well as providing three options - "Cancel" (attempts to ignore the error), "Reset" (clears any actions queued on the object), and "Delete" (removes the object). Most of the time, the game will automatically select an option without notifying you, though you may still notice oddities such as Sims "jumping", or resetting. If you have testingcheatsenabled on, the game will always prompt you for any errors that the game encounters. The cheat itself didn't cause those errors - the only part it has behind those dialogs is that it's forcing the game to ask you what to do.
 * Objects encountering errors are not always a sign of corruption. Most of the time, it is simply a piece of custom content, or a poorly made mod/hack. Sometimes, it is due to a fault on the developer's end, such as missing animation scripts. However, if you constantly/repeatedly encounter object errors regarding Sims, game controllers, or portals, and you do not have any custom content installed, it's plausible that this is a sign of corruption.
 * Object errors may also provide benefits too. Often, when a mod/hack is not working, the creator may ask you to provide an error log, which are generated automatically when an object error dialog is shown. The error log enables the creator to troubleshoot the issue and update the mod to fix the problem.
 * Sims that have a character file are safe to move in/make selectable/tamper with.
 * All Sims have a character file - it's not whether the Sim has a file or not, but rather whether that file is complete and has a complete set of data.
 * Bulldozing a lot will cause corruption.
 * While it is understandable that, seeing how deleting just about anything in the game could cause corruption, deleting lots will remove certain references that the game requires, and doing so will corrupt the neighborhood. While lots that can be lived in (e.g. Dorms, Residential, Apartments, etc.) do contain references to Sims that previously lived there, bulldozing them from the neighborhood won't cause corruption. However, you should always move Sims out of/sell an owned community lot before you bulldoze it.
 * Moving an occupied or previously occupied lot into the lot bin will cause corruption.
 * If it's an in-game feature that's available without cheats, it's safe.
 * As we all wish this were the truth, it isn't. Examples include the family bin delete button, the ability to move occupied lots into the lot bin, the ability to date the Social Worker, etc. Those are things you can do without the help of cheats, mods, or hacks, and they will cause corruption.
 * A thought/speech bubble with squiggly lines means the neighborhood is corrupted.
 * As mentioned above, "not all listed symptoms may mean corruption". Thought/speech bubbles with squiggly lines in them have been sighted in clean, healthy neighborhoods as well. Some symptoms of corruption are also seen with poorly made custom content or hacks. As long as you never attempt the actions listed in this article, and as long as you routinely clean it with the HoodChecker, it should last a very long time.

"I did one of the things that I was told not to do, otherwise it would cause corruption, and nothing bad has happened. It must be safe!"
This deserves a section of its own because it is so dangerously wrong. Just because nothing bad happens as soon as you do something doesn't mean it's safe! Think about the ingredients in hair shampoo, for example. A large amount of those chemicals cause cancer, yet you never emerge from the shower an automatic cancer victim because those chemicals need to build up in your body in order to kill you. Like a virus in incubation, it will show no harmful symptoms, which prompts you to use it again and again. When the symptoms show up, it's far too late to go back. The same goes with corruption - for some people, the symptoms of corruption appear immediately, while other people don't notice anything for months, even years. However, in both ways, it's still corruption, and it will come back to haunt you!