I did what you suggested. In addition I tried every older version until one worked. Finally version 1.17.1 worked. I looked at the change log for version 1.17.2 and the only thing changed was a fix for Scripts and compatibility with JRTO.
Could this interfere with the activation of the plugin.
I made a clean install and experimented on that. sys info under are for my dev install.
truls
### Begin System Info ###
Multi-site: No
SITE_URL: https://eshop.tyfondev.com
HOME_URL: https://eshop.tyfondev.com
Jigoshop Version: 1.7.1
WordPress Version: 4.2.2
Platform: Apple
Browser Name: Safari
Browser Version: 8.0.6
User Agent String: Mozilla/5.0 (Macintosh; Intel Ma
c OS X 10_10_3) AppleWebKit/600.
6.3 (KHTML, like Gecko) Version/
8.0.6 Safari/600.6.3
PHP Version: 5.4.21
MySQL Version: 5.5.42-cll
Web Server Info: Apache/2.2.25 (Unix) mod_ssl/2.2.25 OpenSSL/0.9.8e-fips-rhel5 mod_bwlimited/1.4 mod_fcgid/2.3.6
PHP Memory Limit: 256M
PHP Post Max Size: 8M
WP_DEBUG: Enabled
WP Table Prefix: Length: 6 Status: Acceptable
Show On Front: page
Page On Front: 30
Page For Posts: 0
Session: Enabled
Session Name: PHPSESSID
Cookie Path: /
Save Path: /tmp
Use Cookies: On
Use Only Cookies: On
UPLOAD_MAX_FILESIZE: 12MB
POST_MAX_SIZE: 8MB
WordPress Memory Limit: 128MB
WP_DEBUG: P?
DISPLAY ERRORS: N/A
FSOCKOPEN: Serveren din st?tter fsockopen
ACTIVE PLUGINS:
Headway Connect for Jigoshop: 1.3
Jigoshop: 1.7.1
Jigoshop – Bring: 1.0.0
ManageWP – Worker: 4.1.7
Query Monitor: 2.7.4
Types: 1.7.3
Ultimate Branding: 1.8.1.5
WPMU DEV Dashboard: 3.5.3
WP Views: 1.9
CURRENT THEME:
eShop: 1
### End System Info ###