7 months ago - MrFreake_PDX - Direct link
If you check your error.log in documents/paradox interactive/stellaris/logs/ and the last line says:
virtualfilesystem_physfs.cpp:1202]: Could not open file: settings.txt, error: permission denied

Then try this:
On the drive where Stellaris is installed (C:\ in this case), create a new folder called stellarisdata. The path to this file (in this example) should be c:\stellarisdata.

Then, on Steam, right click Stellaris, Properties and in the launch options box, add:
-userdir=C:/stellarisdata

and then load the game. After loading the game, you can move your user_empire_designs.txt and save games from documents/paradox interactive/stellaris into the new stellarisdata folder you've created