In short: Why Split Archives?
This article breaks down exactly what 00278.7z.002 means, why files are split this way, and how to successfully extract the data within. What is a .7z.002 File? 00278.7z.002
Ensure you have 00278.7z.001 , 00278.7z.002 , and any subsequent files in the same directory. In short: Why Split Archives
If one part was not downloaded completely, the extraction will fail. Re-downloading the specific broken part usually fixes this. Conclusion why files are split this way