Compare the size of Part 10 to the other parts. If it’s significantly smaller (and isn’t the very last part of the set), it's likely an incomplete download.
If you're getting an error that download.part10.rar is not a RAR archive, it usually means the file didn't download completely or is corrupted. Here are a few ways to fix it: Download part10 rar
The most common cause for this error is a broken download. Try downloading Part 10 again from the original source . Compare the size of Part 10 to the other parts