Comment # 3 on bug 1222695 from Petr Gajdos

Yeah, more info would be beneficial to understand what issue you are facing. On
Tubleweed and 15.5:

as root:

# lensfun-update-data 
Reading http://lensfun.sourceforge.net/db/versions.json …
Reading http://wilson.bronger.org/lensfun-db/versions.json …
Successfully updated the database in /var/lib/lensfun-updates/version_1.
#

as a user:

$ lensfun-update-data 
Info: root privileges needed for updating the system database.
Info: updating user DB in '/home/user/.local/share/lensfun/updates'
Reading http://lensfun.sourceforge.net/db/versions.json …
Reading http://wilson.bronger.org/lensfun-db/versions.json …
Info: No newer database was found for last installed Lensfun.
$

Just random thoughts without knowing much about lensfun:
Is it new in 15.6 and wasn't present in 15.5?
Some forgotten alias, somewhere?
Do you have lensfun-data package installed?