Patching to the most recent patch not working

I have been trying to update to 1.48 for the past two weeks and I am constantly getting the same error. It goes through the whole process of installing the update, downloading it from origin and then doing the update with the launcher. As soon as it gets to the end of the update it stops working and says something along the lines of 'invalid file found' Any clue how I can fix this? Also when I do update does that mean I have to replace certain files, since I've downloaded expansion packs from this site?

Using the manual patch completely bypasses the need to update using the launcher. If you would like to update using origin and the launcher, however, you can use the ultimate fix. The following link has instructions to follow, and links to both of the above mentioned fixes to your problem.
https://games4theworld.forumotion.com/t1171-must-read-how-to-install-the-sims-3-correctly