All my personal "actions" vanished after update to the newest version of PS. Seriously?

This happened to me as well - I downgraded a couple versions back to version 25 and they were all there. From there you can export the actions, re-update and load them into version 26

​@Paul Tt - Sorry to hear of your troubles, I wrote a blogpost on this sadly all too common issue:

https://prepression.blogspot.com/2017/01/photoshop-custom-action-file-backup.html?m=1

One should manually save out each action set "folder" individually to a .atn file using the menu on the upper right of the action panel window.

Loaded .atn files or newly created and unsaved action sets are temporarily stored in the Actions Palette presets file (Actions Palette.psp). This file should be considered temporary and may be subject to corruption or loss, which is why making an explicit save to .atn file for each individual action set is strongly advised.

The Actions Palette.psp file can often be used to migrate the entire panel/palette or to possibly retrieve unsaved actions. This is by no means a replacement for saving each Action Set as an individual .atn file. The location of the Actions Palette.psp file can be found in locations similar to:
 

Mac:

• /Users/username/Library/Preferences/Adobe Photoshop CC 2022 Settings⁩/Actions Palette.psp

Win:

• C:\Users\username\appData\Roaming\Adobe\Adobe Photoshop 2022\Adobe Photoshop 2022 Settings\Actions Palette.psp 

(Replace “username” with your user account name and also replace 2022 with your version name/number. The Windows appData or Mac Library directory may be hidden. You can search the web for how to make hidden folders visible for your OS if this is the case).

If you have an older Photoshop version folder or a system backup from before the .psp was reset, then there’s a slim hope that you might be able to recover your actions.