Recently i reinstalled the whole game + lastest patch and everything work fine, but no matter what, if i try to install any script mod, not matter the content, i always get this error message when starting the game:

Error [modsignsimproved]game\temp.ws(8410): Could not find function 'AddSessionTag'
Error [modsignsimproved]game\temp.ws(8415): Could not find function 'RemoveSessionTag'
Error [modsignsimproved]game\temp.ws(10152): Cannot call exec function 'XDPPrintUserStats' from scripts instead of the console.
Error [modsignsimproved]game\temp.ws(10157): Cannot call exec function 'XDPPrintUserAchievement' from scripts instead of the console.
Error [modsignsimproved]game\temp.ws(10437): Could not find function 'SetGameProgress'
Error [modsignsimproved]game\npc\npc.ws(1479): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\npc\npc.ws(2082): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\player\player.ws(1066): Could not find function 'LogWithLabel'
Error [modsignsimproved]game\player\r4player.ws(7621): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\player\r4player.ws(10236): Could not find function 'LogWithLabel'
Error [modsignsimproved]game\player\r4player.ws(12140): Could not find function 'LogWithLabel'
Error [modsignsimproved]game\player\playerwitcher.ws(3145): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\player\playerwitcher.ws(3494): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\player\playerwitcher.ws(3920): Could not find function 'LogWithValueStr'
Error [modsignsimproved]game\player\playerwitcher.ws(4299): Could not find function 'LogWithLabel'
Error [modsignsimproved]game\components\inventorycomponent.ws(137): Could not find function 'LogWithValue'
Error [modsignsimproved]game\components\inventorycomponent.ws(150): Could not find function 'LogWithValue'
Error [modsignsimproved]game\components\inventorycomponent.ws(669): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\components\inventorycomponent.ws(1973): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\r4game.ws(1566): Could not find function 'SetCommonStatI32'
Error [modsignsimproved]game\gui\hud\hud.ws(998): Could not find function 'LogWithLabel'
Error [modsignsimproved]game\gui\hud\hud.ws(999): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gui\hud\hud.ws(1003): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gui\menus\inventorymenu.ws(2512): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gui\menus\inventorymenu.ws(2576): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gameplay\alchemy\alchemymanager.ws(286): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gameplay\alchemy\alchemymanager.ws(290): Could not find function 'LogWithLabelAndValue'
Error [modsignsimproved]game\gameplay\leveling\levelmanager.ws(144): Could not find function 'LogWithValue'
Error [modsignsimproved]game\gameplay\leveling\levelmanager.ws(153): Could not find function 'LogWithValue'
Error [modsignsimproved]game\gameplay\leveling\levelmanager.ws(223): Could not find function 'LogWithValue'
Error [modsignsimproved]game\gameplay\ability\playerabilitymanager.ws(250): Could not find function 'SetCommonStatFlt'
Error [modsignsimproved]game\gameplay\ability\playerabilitymanager.ws(281): Could not find function 'SetCommonStatFlt'
Error [modsignsimproved]game\gameplay\ability\playerabilitymanager.ws(400): Could not find function 'LogWithValueStr'
Error [modsignsimproved]game\gameplay\ability\playerabilitymanager.ws(1295): Could not find function 'LogWithValueStr'
Error [modsignsimproved]game\player\states\vehicles\usevehicle.ws(1600): Could not find function 'LogWithValueStr'

Anyone with similar problems? Attempted to also add the file mentioned in the long inside the mod folder but nothing, also attempted to use the script studio, but crash every time i tell it to create a new mod

You are having issues with a third party user made mod. You need to contact the mod author.

I have no mod installed, freshly new game with the last patch, i originally played with 1.2 and now uninstalled everything and reinstalled

The error appear no matter what script i put in the mod folder, even vanilla untouched script give me the same output

Putting anything into the mod folder is modding the game. The mod folder is not an 'override' folder. You can't just dump stuff in there, vanilla or not.

Finally found out why, for some reason my installation was not installing a main script and the missing references where pretty much screwing everityng up

I found the solution here after some searching, apparently this problem is quite common:
http://forums.cdprojektred.com/threads/56044-How-to-solve-script-compilation-issues-when-launching-the-game-with-mods

This is the solution:

I've installed mod tools and compared the scripts directory contents found in r4data with the one in \The Witcher 3 Wild Hunt\content\content0\scripts\.
I've found that my installation of a game was missing one script: \The Witcher 3 Wild Hunt\content\content0\scripts\engine\telemetryKeyw ord.ws.
I copied it over and no more script errors.

CDPR/GOG Please Fix The Setup

The problem is just on your side.

It will happen if you use certain script mods - these are also mods. I had the very same issue and solution on my end.

Apparently someone isn't capable of reading:

http://forums.cdprojektred.com/threads/56044-How-to-solve-script-compilation-issues-when-launching-the-game-with-mods

READ BEFORE POSTING

That's was NOT, only a problem i had, and considering i installed the game from zero, it's a setup problem not containing the files, as i used NO MODS before attempting to compile, nor i installed anything else on the game, beside official DLC

NOPE!!!!

Here why:

https://www.gog.com/forum/the_witcher_3_wild_hunt/witcher_3_not_launching_scripts_failing_to_compile

Read the above post with the solution at the end, and you will get this:

https://www.reddit.com/r/witcher3mods/comments/3h44vx/for_anybody_having_script_compiler_errors_using

Apparently it's a common error if you install the game from version 1.6 and the patch with the last 1.8.4, the higher available patch before 1.10 came out

To conclude the argument, i would also like to point out HOW I DIDN'T HAD ANY MOD INSTALLED, so they could not have been the culprit