I have no clue if this is the EXACT mod that gives me this error. But I've been trying to install the world Boroughsburg & when I clicked install in the launcher it said "It looks like you have installed an unofficial game modification that does not match your current version of the Sims 3.." I tried to google the issue & I haven't got anything! I looked on the creator's Tumblr page to see that the world was built with the 1.67 patch. ( my current version ) I also tried to contact the creator but I haven't been able to find any contact information. Can someone help me?

I don't know about the world or this error note, but

I would recommend not to install custom worlds via the launcher.

If you extract the .world file from the sims3pack with https://modthesims.info/d/364038/delphy ... -2009.html

You can rename the . world file with the world name like Boroughsburg.world
and then copy it to your game installation folder not under Documents
The Sims 3 > Gamedata > Shared > NonPackaged > Worlds

This way you can test and easily delete a world if you don't like it.
Do you still get the error with this method?
​​​

There are some important notes about EPs needed, Riverview, CC you need to install (as package files to your mods folder)
maybe you also missed something?

https://potato-ballad-sims.tumblr.com/p ... borhood-in

Usually none of this has anything to do with world installs. Do you get the error if you attempt to run the game as is, without the custom world?

The error should mean that you have a Core Mod installed that does not match your game's patch level. There aren't very many Core Mods in popular usage, but NRaas ErrorTrap is one of them. That is why we offer three different variants of the mod, one for 1.69, one for 1.67/Disc (and 32-bit Mac), and one for 1.67/Steam. Each of these three game install types has a different internal build number, hence Core Mods getting upset about them. All three are available from the same download page.

If you indeed have the correct variant of ErrorTrap in play, then perhaps you have an additional Core Mod that is kicking up the error. Here (scroll down a bit) is where to find the short list of such mods in common usage, that we know about. Another possibility is that you seem to be on the 1.67/Disc version but its patching only appears to be complete though it really isn't. The solution for that issue is to download and run EA's SuperPatcher for 1.67 rather than rely on the Launcher to handle the patching while ignoring any offers to advance to 1.69 as that would unnecessarily bring Origin or now the EA App into the mix. Note that the SuperPatcher should never be run on an Origin/EA App or Steam install as that will break it.

The good news is that if you have a Core Mod made for any 1.67, 1.69, or 1.70 install, then there isn't a real game-related issue and the warning message can be safely ignored (though it would be better to resolve the mismatch to get the warning to stop appearing). Core version mismatches aren't really a thing unless a game install or a Core Mod mismatch goes back to before 1.66 as the game core has not really changed since then other than the internal build numbers.