I'm trying to re-compile a mod to which I have made edits, but when I do so, I get this error

**"psc file validation failed. created backup in**

Why do I get this error, and how do I fix it?

I'm using a mod organizer, and the CreationKit64bit 2021.

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    – Pikalek
    Commented Apr 29, 2022 at 13:48

1 Answer 1


This question&answer is a cross-post of one of my posts on Reddit.

This issue occurs if you have a mod organizer with a virtual folder system, like MO2 run Creation Kit through it. Being used to many mods in the loadout and also keeping mods and installation clean and handling tools, most users use mod manager tools. These are very powerful and helpful, but they also interfere with vanilla executions like the compiler. For mod authors that start working in 2021 and the future, this will be one of the first challenges to overcome. The other issue is the "code not loaded" fix, I posted here.

The compiler has (vanilla setup) only access to your temporarily loaded files (added temporarily by your mod manager) and your steam root directory SkyrimSpecialEdition/Data/scripts. When you now compile, you will usually gain a working and up-to-date compiled binary pex file, which the game is using to run. It will be stored in (modmanagername)/overwrite/scripts (if its a new mod) or (modmanagername)/mods/modname/scripts (if its an existing mod).Same applies for the "text code" source script file (psc), which contains your inputs on the quest fragments of the quest object. It will be stored in (modmanagername)/overwrite/scripts/source (if it's a new mod) or (modmanagername)/mods/modname/scripts/source (if it's an existing mod).

Now, when you load a mod the second time (existing mod), and you have made previous edits, the compiler will look at Data/scripts/source in the vanilla directory to load in the psc. For obvious reasons, this will fail. When you compile, you will get the warning:

**"psc file validation failed. created backup in**

If you now look into steam/.../SSE/Data/scripts/source, you will not find it, because you place your files in the virtual folder system (modmanagername)/mods/modname/scripts/source. If you look there, however, this place is empty, too. You will essentially be stuck here with your first version of the pcs. When you load your quest next time, the quest fragment code will be reverted to what you made before, new edits are gone.

To fix it:

  1. First, you need to manually create a "backup" folder where the compiler is trying to place the source script. add: *(modmanagername)/mods/(modname/scripts/source/*backup AND (modmanagername)/overwrite/scripts/source/backup.
  2. Now, whenever you compile and get this warning, go and look for the psc file, remove the time stamp (pscname_backup_year_date_time -> pscname.psc).
  3. Take it and copy-paste it in your steam directory where the compiler is looking for it. (SkyrimSpecialEdition/Data/scripts/source).


  1. I do not take any responsibility for missing files or broken games, I just share the approach in best faith, with the goal of helping you to find the solution yourself, at your own risk.
  2. I assume that you have changed your ini file for Creation Kit 64bit, hence not a vanilla installation. Instead of* "SkyrimSpecialEdition/Data/source/Scripts" (SkyrimSpecialEdition) i have my psc in "SkyrimSpecialEdition/Data/Scripts/Source" *(LegendaryEdition Structure and convention on some Beyond Skyrim teams to avoid confusion. For a detailed description of how to do that little change in the CreationKit.ini or CreationKitCustom.ini (if you have made one), please refer to the other fix I linked above to see how you change the compilers input/ output folders via Creationkit.ini / CreationkkitCustom.ini.
  3. You only have pex files if you copied them in manually, compiled them already, or pasted a mod inside. By vanilla setup, the game uses the pex files compressed in a BSA archive, not in the folders you see below, so no sweat if you do not have pex files at all yet. The compiler however needs the input folder and the psc as source files, and the output folder where to place the pex files.
  4. If you changed your ini and look for different folders, then of course, you must place your files in these new locations.
  5. Thank you to everyone working with me on Creation Kit contents, especially Elscrux, Woni, and Tascani. This is mostly a fix for starters, anyone who knows their way around CK is probably aware of this method by logic.

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