Selfoss programe is very helpful to me. There is also some issues, such as duplicate items.
Anyway, I did the upgrade from 2.4 to v2.6 today.
The upgrade procedures are simple. See following upgrade guide. For me, I just did step 1, 2,3.
1. backup your database and your “data” folder
2. (IMPORTANT: don’t delete the “data” folder) delete all old files and folders excluding the folder “data”
3. upload all new files and folders excluding the data folder (IMPORTANT: also upload the invisible .htaccess files)
4. Rename your folder /data/icons into /data/favicons
5. Delete the files /public/all.css and /public/all.js
6. Clean your browser cache
7. insert your current database connection and your individual configuration in config.ini. Important: we change the config.ini and add new options in newer versions. You have to update the config.ini too.