[2020] GOG/Stellaris Launcher instalation failed on most mods.

What launcher version do you see? Current is 2020.14

And, are these mods updated to work with the new game patch 2.8 ?  

Please try the following:

- unsubscribe from all mods
- delete the folder Documents/paradox/Stellaris/mod/
- delete the file Documents/paradox/Stellaris/mods_registry.json
- delete the file Documents/paradox/Stellaris/launcher-v2.sqlite
- subscribe to a few mods
- run the game up and see if those mods are now available to you.

I hope that does it for you!  

Then I don't know why this is not working for you. Do the mod files appear in that /mod/ folder okay, after you run the launcher?  

miguelmonte said: the files i can find, yes. but never the mods_registry.json file.

That is expected as that is not used in recent launcher versions, it's replaced by the sqlite file.

If the mod files are physically present, the launcher is up to date, the game is up to date, and the mods are compatible with that game version ... I cannot think of anything else that can cause this problem. You are still getting "installation of this mod failed", no change in the symptoms with everything we've done here?  

miguelmonte said: only some mods fail instalation... others work just fine it seems

I didn't realise that. You are 100% certain these mods are updated for 2.8 ?  

I guess the ones that fail must have something in common as mods, but what that might be I have no idea, knowing nothing about mods. And why do they fail on your setup but not for others with the same code?

Can you try setting these to run as the Windows Admin user?
dowser.exe (in the GoG Stellaris folder)
C:/users//AppData/Local/Programs/Paradox Interactive/bootstrapper-v2.exe
C:/users//AppData/Local/Programs/Paradox Interactive/launcher-v2.2020.14/paradox launcher.exe  

Can you do a test install on some other machine, to see if the problem happens there too?