The jblnqp portion is simply the unique name given to the archive by the person who created it. The Problem: "Unexpected End of Data"
Make sure all numbered volumes of the archive are in the same folder on your computer. jblnqp.7z.001
Demystifying the jblnqp.7z.001 File: What It Is and How to Open It The jblnqp portion is simply the unique name
How to Extract .7z.001 files - Microsoft Q&A why it’s named that way
In this post, we’ll break down what this file type is, why it’s named that way, and exactly how you can extract its contents. What is a .7z.001 File?