Installed WP on sites.wikimedia.se following these instructions. Pointed new.umepedia.se to the WP site.

I managed to import the database from the old server. Had to change siteurl and home in wp_options to the new server URL.

After importing a couple of themes from the old site, the new one is now up and running. Some things are still missing, e.g. header images.

The plugin used to show header images is no longer maintained. If we want to keep them we need to find another plugin.

Take a look at the theme, if it's easy to update the custom theme with the new WP-parent theme. If so do that else skip for now. Make sure to save the old theme files in that case.

The map doesn't work, either on old or new site.

I went through the plugins on the old site. Many are old, outdated and/or don't work anymore. Below is a list of them and which ones are now activated on the new site.

❌ Cimy Header Image Rotator - No longer maintained. A not as fancy alternative is to use the built in random header image, but that doesn't work with Polylang (see below).
❌ Core Control - Couldn't find, info page no longer exists.
❌ Mobile Smart - Fatal error when trying to activate. Probably not needed now, WP seems responsive enough.
✔ Polylang - Makes the header image go away if random uploaded image is used.
❌ Print, PDF & Email by PrintFriendly - Not GDPR compliant.
❌ Rotating Tweets (Twitter widget & shortcode) - Couldn't publish after adding widget.
✔ The Events Calendar - Not sure where this actually shows up. Couldn't find it on the old site.
✔ Twenty Eleven Theme Extensions
✔ WP-Matomo Integration - It says it's working, but nothing is showing up in Matomo yet. The plugin was activated, but not working on the old site. No visits shows up in Matomo.

All active plugins are set to auto update.

Redirected www.umepedia.se to the new server. Some links (e.g. main page) still points to new.umepedia.se. I don't know why that is, hopefully it's because of a cache somewhere that will sort itself out.

The link that was pointing to new. has been fixed. This happened after I installed Certbot (T310891). Not sure if it was because of that, but at least it works now.

The database for Umepedia takes up quite a bit of space, 1.5 GB. Almost all of it is the table wp_posts which has nearly 300,000 records. I tried a couple of WP plugins to optimise the database, but they didn't do much. Ultimately I know too little about WP to say if it's normal that a fairly small site takes up this much space.