Error Code 13

CRUZADO_101​  Please post a screenshot of the error.  I don't recognize it and would like to know what it looks like, at least.

I don't know whether this will corrupt your save, or already has, but I would be extremely wary of using any Gallery content that threw any error at all.  The For Rent patch broke a lot of Gallery uploads that were previously fine and safe to use, and installing them can definitely corrupt a save.  It appears that some subsequent patch(es) broke more content, although it's less clear what the trigger was, but what is obvious is that these uploads can corrupt saves too.

I was not able to take a screenshot on it, as it  goes away when I load to a different lot and save it but I'll take it next when it happens again. 

Hello! I started a new save and got error code 13 again while building. I'm honestly so scared for my savefile right now. Can you please help me, it does work if I use save as but I am scared if it will continue to corrupt. I put the screenshots below! This started after the update

While putting pieces together, this syarted whenever I set up a small businesss and use mods for activities. I will try to make another small business without using mods

CRUZADO_101​  I've merged your new posts with your existing thread to keep everything together.  Please let me know if this happens with no mods or custom content present.

This does not happen if there are no mods in activities for small business venue. I was able to get by and fix it by using save as and tried making another small business with no mods in it

I got this error message too. I downloaded a lot off the gallery. I was continually saving while fixing it up and never got the error message. I got the message when I opened my small business. I have no mods downloaded nor have I ever used them, I was always too scared of them. I deleted all of my save files besides the one I got the message for and I still got the message. I just repaired the game and that seems to have helped so far. 

I can't repair them since I bought my packs on steam so I don't get any repair option in ea app huhuhu. But I guess it is from small business. First time I have ever encountered this

CRUZADO_101​  Glad to hear that worked for you.  To repair the game in Steam, right-click the Sims 4 tile and select Properties > Installed Files > Verify integrity of the game files.

ShaeNotShea​  If you see this error again, please test with a different lot.  Even though mods and custom content don't transfer through the Gallery, their effects can.

I'd also like to take a look at the lot you downloaded even though the repair may have fixed the issue.  If you're willing, please link it, or else name the creator and lot so I can find it myself.

I’m currently having the same issue. I noticed it started around the time I started a small business