CUSTARD: Corrupt (Not a DBPF) / Bad Download / Bad Index

There is always one package that has a bad index or is a bad downlaod.

Asking Delphy about is, that was his answer

Basically, I define a "bad download" as "it's a DBPF but it can't be read". Specifically it's talking about the fact that the index offset points *outside* the bounds of the file. Which obviously is corrupted. This differs from a bad index, which is when the index itself exists, but had bad or invalid compression flags. (Which can be fixed). 

Once such an download is encountered, the rest of the package files are completely messed-up. They are simply put, not package files anymore. I think that because of that one bad download/index, the rest could not be uploaded properly, resulting in this problem. Since those files cannot be opened with any tool, I have no idea what those items are. Sims3Packs like that cannot be installed. You'll get an error.

Custard shows them like this:

Sims3Packs that are faulty like this are houses most of the time. If you really want to keep it, you can try removing all red package files with Custard (don't know if it will work, do so at your own risk)

Further Reading
TUTORIAL: Custard