I have been trying to upload a sim with no CC to the exchange so I can change my page avatar. Every time in CAS it says Export failed. Its been happening for about a month now. I tried google searching and found an old forum post but no one seemed to know a fix. Does anyone know how to fix this. I have had the same problem with CAP saying export failed. I normally just uninstall and reinstall it work. Please tell me I don't have to do the same for my sims 3 games.  
FYI: I even tried just a plain jane default sim to upload it didn't work either.
I wasn't sure where to put this so I hope i'm on the right forum sorry if i'm not.
I do have a mod for the background right now but even with taking all my mods out it still doesn't work.

I had a problem like this on my old computer after one of the patches and was able to fix it as follows: (Note, you have to do this every time you want to export a sim to the exchange.)

You can cut your DCCache folder (located here: C:\Users\Marnie\Documents\Electronic Arts\The Sims 3) and paste it to your desktop. Then you should be able to sign into the game, go to CAS, export your sim to the launcher and then upload it to the Exchange. Then take the same DCCache folder that you moved to your Desktop and put it back where it was, just write over the new one the game created. I've tried this with no problems and you don't have to reinstall any files. If you don't put this folder back, you have to reinstall all your sims3pack files via the launcher.

I suspect this error is happening because there's a corrupt Sims3pack file in the Downloads, but until you locate it, this is a work around.

Thank you so much! It worked Yay!!!  

We have some AWESOME members and friends here don't we!!!!!!!!!      Thanks for helping her Eden!! 

Yay, I'm so glad it helped you. I remember the frustration I was having when this problem started for me. All I wanted was to upload a darn Sim to the exchange and it just wouldn't work. I hunted and hunted around until I found that fix, but I forget where.