Lightroom Classic 5.7 terminates while importing files

Lr/5.7 and Windows 8.1 are both anchient and I’m surprised the user has been able to keep them both running this long.   Needless to say, the world of viruses, malware, and hackers has progressed by leaps and bounds since then and unless this system is air-gapped (no internet access) it is very vulnerable to attack.  Hopefully the user is running an up to date antivirus tool and not just one left over from 2015.   

So, as ​@dj_paige suggested,. try replacing the Preferences file.   If that doesn’t do it, try reverting to a backup catalog (if you have any) from before this problem started.    

As you may or may not know the “expected’ average life span of a spinning disk drive is 3 to 5 years with average use and 6ish years with light use in ideal conditions.  If your rig is original equipment it’s over 11 years old (LR/6.0 came out in May 2015) - well past any measure of expected life span.  If that’s the case we could be looking at a failing drive, bad cables, failing memory, failing CPU, weak power supply, or any number of other hardwar/sofware/firmware problems due to age.

If you still have the Windows and Lightroom install disks, you could try porting your system to newer hardware.  As you are on Windows, I think it is possible to install and run Lr/5.7 on more recent versions of Windows as well. 

BTW  Lightroom CC 2015.10 (LR/6.10) was the last perpetual license version the shipped.  Since LR/7.0 it was subscription only.  

Good luck. 

Lightroom-version: 5.7 [991162]
Licenstyp: Perpetual
Operativsystem: Windows 8.1 Business Edition
Version: 6.3 [9600]
Programarkitektur: x64
Systemarkitektur: x64
Antal logiska processorer: 6
Processorhastighet: 2,8 GHz
Internt minne: 8190,1 MB
Fysiskt minne tillgängligt för Lightroom: 8190,1 MB
Fysiskt minne använt för Lightroom: 836,9 MB (10,2%)
Virtuellt minne använt för Lightroom: 807,2 MB
Storlek på cache-minnet: 188,6 MB
Högsta antal trådar som används av Camera Raw: 6
System-dpi-inställning: 96 dpi
Skärmdisposition är aktiverad: Ja
Bildskärmar: 1) 1920x1080, 2) 1920x1080, 3) 1360x768

Programmapp: C:\Program Files\Adobe\Adobe Photoshop Lightroom 5.7
Bibliotekssökväg: E:\Lightroom\Lightroom.lrcat
Inställningsmapp: C:\Users\herte\AppData\Roaming\Adobe\Lightroom

Installerade plugin-program: 
1) Behance
2) Direktfångst Canon
3) Direktfångst Leica
4) Direktfångst Nikon
5) Facebook
6) Flickr
7) ON1 Photo RAW 2020
8) ON1 Resize 2020

Config.lua-flaggor: None

Adapter #1: Leverantör : 1002
    Enhet : 68ba
    Delsystem : 3fe1043
    Revision : 0
    Videominne  : 1010
Adapter #2: Leverantör : 1002
    Enhet : 68ba
    Delsystem : 3fe1043
    Revision : 0
    Videominne  : 3f2
Adapter #3: Leverantör : 1414
    Enhet : 8c
    Delsystem : 0
    Revision : 0
    Videominne  : 0
AudioDeviceIOBlockSize: 1024
AudioDeviceName: Högtalare (Realtek High Definition Audio)
AudioDeviceNumberOfChannels: 2
AudioDeviceSampleRate: 44100
Build: Uninitialized
CardID: 26810
Direct2DEnabled: false
GPUDevice: D3D
MaxTexture2DSize: 8192
OGLEnabled: true
Renderer: AMD Radeon HD 6700 Series
ShaderModel: 11.1
Vendor: AMD
VendorID: 4098
Version: 1002:68ba:3fe1043:0000

There is no Lightroom Classic 5.7

Perhaps you mean the very old (probably 12-15 years old) Lightroom. Or perhaps you mean something else. Can you go to Help->System Info and show us the top 10 lines so we can be clear about what actual software you are referring to?