Do you want to keep only the users and get rid of all the content you users posted during all those years? If you just export/import the users you will lose ALL CONTENT (including messages and any uploaded files). Is this really what you want? If not, you need to upgrade your site from 1.8 to 3.0 step-by-step (1.8->1.9->1.10->1.11->1.12->2.3->3.0 - yes, you can upgrade from 1.12 directly to 2.3 but do not omit 1.9 - 1.12). You would also need to have compatible versions of any 3rd party plugin for the corresponding Elgg versions.

Well, I'm still weighing my options. My users seem to want a less bloated site with fewer options (plugins) and a more easily navigable interface. I think like me they're getting old! I could no doubt re configure 1.8 to meet their needs. But I wouldn't mind starting over with the latest Elgg version.

So far as a total update is concerned, you cautioned me similarly a year or two ago. I know it would drive me crazy. Elgg 1.8 is a long way from 3.0, and I made loads of changes to everything except the engine. Also I never bothered updating anything as my site runs in walled garden mode.  It runs itself perfectly with little attention from me.

I'll give this more consideration before doing anything drastic. Meanwhile I'm still curious to know how to transfer just the members' display name, user name, email address and password using CSV. The posts on the site that mention using CSV for this are all years old.

Thanks' for your time  iionly and all your help in the past.