Fallout 4 Downgrader Mod

After Fallout 4’s Next-Gen update, many mods stopped working due to changes in the game’s files. The Fallout 4 Downgrader tool allows you to quickly revert your game back to the pre-update version, restoring compatibility with mods like F4SE (Fallout 4 Script Extender), Buffout 4, and more — all without needing to log in.

Quick Start:

Download FO4Down.zip

Extract it anywhere on your PC

Run one of the following:

Downgrade By Patching Files.bat

Downgrade By Downloading Depots.bat

Downgrade by Patching Files:

Works only if you already have the Next-Gen executables installed

Leaves Next-Gen data files intact

Requires additional plugins to work

To also install plugins automatically, run:

Downgrade By Patch Files and Install Plugins.bat

Downgrade by Downloading Depots:

Downloads the entire old version of the game

Replaces all files, including executables and data files

May take longer depending on your connection speed

Notes & Troubleshooting:

If you installed patching plugins and later downgrade by depots, you may need to remove:
/Fallout 4/Data/F4SE/Plugins/Backporter Archive2 Support System.dll
if you experience CTD on startup

Running FO4Down.exe:

First tries patching files automatically

If patching is not possible or already done, it will fall back to Steam depot downloading (Steam login required)

Version 1.0.6.3 and newer will:

Verify file versions

Fix cases where Fallout4.exe incorrectly reverts to v1.9.4

FAQ:

• The application won't start. What should I do?
  • If you downloaded the small zip file: You need to install the .NET 8 runtime because the program requires it to run. You can download the larger zip file instead, which includes everything needed and skips this step.
• Where do I extract the files?
  • You can extract the files anywhere on your computer. The application will automatically locate your Fallout 4 installation, no matter where it is!
• My computer ran out of space while downloading the depots. Can I change where it's saved?
  • Yes, simply move the entire folder containing FO4Down.exe to a different drive. When you run it again, it will pick up where it left off.
• Why does the application need my username and password?
  • To download the necessary files, the application needs to verify your identity and check if you own Fallout 4 through Steam. Your login details are only used for this purpose. For more details, see our security disclaimer.
• Can I log in using a QR code?
  • Yes, you can! In the login window, choose the "QR" option or use the 'FO4Down - Login with QR.bat' file. Alternatively, you can manually add the -qr flag when running the application.
• How do I download the game in a different language?
  • When starting the application, you can select your desired language. The app will attempt to match the language you already have installed and secondly the system's language settings or you can specify the language using the command -language followed by the language code (e.g., -language Spanish). English is the default if no language is specified. To download all languages, use the -all-languages flag.
• I chose a different language, but everything is still in English. What should I do?
  • I am currently fixing this issue. In the meantime, update the Fallout4.ini and Fallout4_default.ini files in your /Fallout 4/ folder to include the new language files. If there are duplicate files in different languages, delete the unwanted ones.
• Does this also downgrade the Creation Kit?
  • Yes, just select the "Downgrade Creation Kit" option in the settings. This will automatically be selected if you already have the Creation Kit installed.
• How can I stop Steam from updating my game after a downgrade?
  • To prevent updates, follow these steps outlined in this video: How to Prevent Steam Updates. Essentially, navigate to "Steam\steamapps", find "appmanifest_377160.acf", right-click, go to Properties, and check "Read Only".
• The game crashes soon after starting post-downgrade. What can I do?
  • First, make sure to delete all Creation Club files in the /Fallout 4/Data/ folder. These files start with "cc" and can cause crashes. You can also enable "Delete creation club files" when starting the application to automatically remove them. If the game still crashes, double-check the Data folder for any leftover files.