When this Fallout: London build refuses to start, launch it from the FOLON launcher, match the right Fallout 4 version, and apply the latest patch.
Stuck at a black screen, instant crash, or a launcher loop? You’re not alone. This guide explains why the total conversion refuses to boot and gives a clean, step-by-step path to get you playing. You’ll see the main version mismatches and the correct way to start the game.
Quick Diagnosis And The Two Golden Rules
Before you dive into deep fixes, run two quick checks. First, always start the mod with its own launcher or the F4SE loader configured for it. Second, make sure your base game matches the build the mod expects. Many failed starts trace back to those two points.
| Cause | What You See | Fast Fix |
|---|---|---|
| Wrong Fallout 4 version | Logo flash then exit | Use the pre-next-gen build the mod targets or a downgrader |
| Starting from Steam Play button | Vanilla boots or auto-updates | Start from the mod’s launcher or F4SE loader |
| Missing DLC / incompatible language build | Immediate crash | Install GOTY with all DLC in English |
| Outdated London files | Launcher loop | Run the mod’s updater in its install folder |
| INI settings or disabled ESM/ESP | Hang on load | Regenerate INIs; enable all required plugins |
| Conflicting mods | Crash during intro | Test with a clean profile made for London |
Why The London Mod Won’t Launch
The team built the project against a specific pre next-gen Fallout 4 build. When Bethesda shipped the next-gen updates, core files and the scripting extender changed, which broke many fan projects until patches landed. If your Steam copy updated or you installed a fresh console-oriented build, the loader won’t find the functions it expects and the process dies.
Fix it by aligning the base game. GOG players can install the classic PC build more easily. Steam players usually need a small downgrader and must avoid the platform’s Play button for this title. After you match versions, run the mod’s launcher once so it can verify paths and patch the right files.
Clean Install Path That Works
Step 1: Start From A Working Vanilla Base
Uninstall any half-finished attempts. Install Fallout 4 GOTY. Launch vanilla once to generate the settings files.
Step 2: Match The Expected Build
If you use Steam, apply a downgrader to reach the required PC build referenced by the project’s release notes. Lock out auto-updates. If you use GOG, follow the store page’s steps to add the mod to your library and pull the offline installers or use Galaxy.
Step 3: Install The Mod To Its Own Folder
Run the dedicated installer. Point it to a simple path outside Program Files. Let the installer finish and create a desktop shortcut for the launcher.
Step 4: Update, Then Launch From The Right EXE
Open the launcher inside the mod’s install folder. Hit Update until it reports you’re current. Then start via the f4se_loader that the launcher set up. Don’t boot from Steam for this profile.
Step 5: Start A New Save
Patches and the first DLC changed core records. A fresh save avoids bad references from older runs and keeps you on the supported path.
Tell-Tale Errors And Targeted Fixes
Black Screen After The Logo
This points to a version gap or a missing plugin. Recheck the base game version, then confirm that all ESM and ESP files that ship with the project are enabled in your mod manager.
Launcher Opens, Then Closes
Open the mod’s install directory and run the installer or launcher as admin once. If it keeps closing, delete the cache inside the launcher subfolder and run Update again.
Vanilla Starts Instead Of London
You pressed Play in Steam. Close it, then use the desktop shortcut created by the installer or run the f4se_loader.exe in the base game folder that the launcher configured.
“File Directory Is Corrupted” On GOG
Re-download the offline installer from your GOG account page, then verify the files via Galaxy. Install to a short path and rerun the launcher update.
What The Developers And Bethesda Have Said
The release lined up with older Fallout 4 PC builds. Bethesda’s next-gen patch for Fallout 4 on April 25, 2024 changed core files that many mods rely on, so the team delayed and retooled the release to keep the project stable. You can read the official Fallout 4 next-gen update notes for the changes that landed.
Settings That Prevent Sticky Starts
Once you’re on the right build, a few small tweaks save time. Keep cloud saves off for this profile, set both display width and height in Fallout4Prefs.ini, and make sure the game and the project both run with write access to their folders.
INI And Plugin Hygiene
Delete the INI files in Documents\My Games\Fallout4 so they regenerate after the vanilla run. Then open your mod manager and check that every master plugin for the project is active and in the expected order.
Controller, Overlay, And Antivirus Notes
Disable overlays for the first run. Add the mod’s folder to your antivirus allow list. If a controller causes a hang on the splash screen, start with keyboard and mouse, reach the main menu, then plug the controller back in.
Steam Vs GOG: Which Start Is Smoother?
GOG offers a cleaner path for PC users since its build aligns with the target version and avoids the Steam auto-update trap. Steam can work fine once you lock the version and launch from the correct shortcut. If you swap platforms later, do a clean install and avoid mixing files.
| Platform | Pros | Watch Outs |
|---|---|---|
| GOG | Straightforward install; offline installers | Use the mod’s launcher; verify downloads |
| Steam | Easy base game access | Disable updates; never press Play for this profile |
| Either | Mod runs well once aligned | Start new saves after big patches or DLC |
Patch, DLC, And Save Game Reality
Big patches changed quest scripts, world edits, and records. The first DLC shipped with thousands of fixes plus new content, and the team recommends a fresh run to avoid stale data from older saves. If you want to keep a legacy save for nostalgia, back it up to a dated folder and label it clearly.
Version Alignment Checklist
Keep Your Paths Simple
Install both the base game and the mod somewhere like D:\Games\Bethesda to dodge permission snags. Avoid spaces and deep folders inside your modded profile.
Lock The Base Game
On Steam, set updates to only happen when the game launches, then never launch from Steam for this profile. Keep a small text note in the folder that reminds you which EXE to use.
Back Up The Load Order
Export your plugin list after every clean run. If something breaks later, you can restore the last good state in seconds.
Recheck After Driver Updates
GPU drivers can flip settings like shader cache and overlays. If you updated drivers and the game stalls at the splash, toggle borderless windowed and try again.
Common Pitfalls To Avoid
Don’t mix files across platforms. Don’t push the Steam Play button for this profile. Don’t install inside Program Files. Don’t add big overhauls on top of the project until you’ve completed the opening hours on a clean save. These small habits prevent most launch headaches.
Performance Tips For First Boot
Set a frame rate cap that matches your display. Keep texture mods out of your first run. Once you reach the hub area and confirm stability, raise settings one at a time. If you want extra crash protection, add Buffout 4 and its prerequisites to your mod manager profile tailored for this project.
Troubleshooting By Symptom
Instant Desktop With No Error
That usually means the loader found the wrong runtime. Reapply the downgrader or reinstall the GOG version, then rerun the launcher update.
Stuck On Loading After New DLC
Start a new save and let the scripts initialize in a quiet area before fast traveling. If it still hangs, verify the DLC files inside the launcher and reinstall the last patch.
Audio Plays, Screen Frozen
Set a borderless window, drop the resolution, and delete the renderer cache in Documents. Then try again from the launcher.
Clarifications Players Ask About
Support For The Newest Steam Build
Yes, as long as the team supports a compatible loader or you keep a PC build that matches the mod. Many players run it daily on both platforms once the version is right.
Using Other Mods Safely
Keep them to a separate profile. Treat this as a standalone game. If you add extras, do it after you’ve confirmed a stable loop with a new save.
Console Availability
No, this is a PC project only.
Safe Uninstall And Reset
If you tried many fixes and the start still fails, a clean slate often wins. First, back up saves to a separate folder. Next, uninstall the mod from its own directory and delete any leftovers in that folder. Then verify your base game files in your store client. Launch vanilla once. Reinstall the mod to a short path, open the launcher, press Update, and start a brand-new save. This sequence clears broken links, stale scripts, and mismatched INIs that can block the first load.
Where To Get Reliable Install Info
Two pages answer most version and install questions. Bethesda’s official Fallout 4 next-gen update notes list the PC changes that affected many mods, and the project’s official install page explains the expected build and the right way to start the game.
Final Fix Checklist
Launch from the project’s own tools. Match the base game build that the team supports. Update the install from its launcher. Keep cloud saves off for this profile. Start a new save after big patches or DLC. With those steps in place, the start button leads to London, not the desktop, every single time with consistency.