FO4 ctd direct after launching in MO2

[schwarzbrand]

I reinstalled FO4 with steam. Downgraded it to 10.163 via downloading archives and installed some mods and played some test runs.

A few days later the game won't start anymore. MO2 wants to launch the game, the screen goes black for a second or two and then jumps back to MO2. No crash log. MO2 log waits for fallout4.exe, then goes back to desktop.

No missing master, no change in the load order, no limit problems and F4SE installed correctly.

Even launching via steam is not possible anymore.

I deleted the steam game folder and downloaded everthing again. The game starts as the newest AE version. But after downgrade and using MO2 the game won't start anymore.

 

MO2 log:

[2026-08-06 19:46:54.653 D] Updating VFS mappings...
[2026-08-06 19:46:55.382 D] VFS mappings updated, linked 623 dirs and 5 files in 736ms
[2026-08-06 19:46:55.386 D] checking steam
[2026-08-06 19:46:55.386 D] managed game is located at 'C:/STEAM/steamapps/common/Fallout 4' and file 'C:/STEAM/steamapps/common/Fallout 4/steam_api64.dll' exists
[2026-08-06 19:46:55.390 D] 'steam.exe' is running, accessible=yes
[2026-08-06 19:46:55.390 D] spawning binary:
[2026-08-06 19:46:55.390 D]  . exe: 'C:/STEAM/steamapps/common/Fallout 4/f4se_loader.exe'
[2026-08-06 19:46:55.390 D]  . args: '-forcesteamloader'
[2026-08-06 19:46:55.390 D]  . cwd: 'C:/STEAM/steamapps/common/Fallout 4'
[2026-08-06 19:46:55.390 D]  . steam id: ''
[2026-08-06 19:46:55.390 D]  . hooked: true
[2026-08-06 19:46:55.390 D]  . stdout: no
[2026-08-06 19:46:55.390 D]  . stderr: no
[2026-08-06 19:46:55.390 D]  . real cmd: '"C:\STEAM\steamapps\common\Fallout 4\f4se_loader.exe" -forcesteamloader'
[2026-08-06 19:46:55.400 D] process tree:
[2026-08-06 19:46:55.400 D]     f4se_loader.exe, pid=11316, ppid=9028
[2026-08-06 19:46:55.400 D] waiting for completion on f4se_loader.exe (11316), strong interest
[2026-08-06 19:46:55.479 D] process 11316 completed
[2026-08-06 19:46:55.483 D] process tree:
[2026-08-06 19:46:55.483 D]     Fallout4.exe, pid=11080, ppid=11316
[2026-08-06 19:46:55.483 D] waiting for completion on Fallout4.exe (11080), strong interest
[2026-08-06 19:47:02.118 D] process 11080 completed
[2026-08-06 19:47:02.118 D] nothing to wait for
[2026-08-06 19:47:02.119 D] process runner: refreshing because the process completed
[2026-08-06 19:47:02.120 D] refreshing structure
[2026-08-06 19:47:02.122 D] refresher: using 10 threads
[2026-08-06 19:47:02.307 D] refresher saw 71150 files
[2026-08-06 19:47:02.307 D] timing: DirectoryRefresher::refresh() 186 ms
[2026-08-06 19:47:02.308 D] directory refreshed, finishing up
[2026-08-06 19:47:02.308 D] clearing caches
[2026-08-06 19:47:02.308 D] running post refresh tasks
[2026-08-06 19:47:02.308 D] structure deleter thread start
[2026-08-06 19:47:02.340 D] timing: PluginList::fixPluginRelationships 0 ms
[2026-08-06 19:47:02.342 D] timing: PluginList::refresh() 33 ms
[2026-08-06 19:47:02.342 D] timing: OrganizerCore::refreshESPList() 33 ms
[2026-08-06 19:47:02.350 D] refreshing lists
[2026-08-06 19:47:02.352 D] structure deleter thread done
[2026-08-06 19:47:02.377 D] timing: PluginList::fixPluginRelationships 0 ms
[2026-08-06 19:47:02.379 D] timing: PluginList::refresh() 28 ms
[2026-08-06 19:47:02.379 D] timing: OrganizerCore::refreshESPList() 28 ms
[2026-08-06 19:47:02.419 D] timing: OrganizerCore::refreshBSAList() 40 ms
[2026-08-06 19:47:02.419 D] refresh done
[2026-08-06 19:47:02.419 D] timing: OrganizerCore::onDirectoryRefreshed() 110 ms
[2026-08-06 19:47:02.628 D] timing: MainWindow::checkForProblemsImpl() 5 ms

[plutocene]

Without a crashlog a guess, I think you forgot to downgrade a .dll of a newly installed mod or its incompatible.  Get https://www.nexusmods.com/fallout4/mods/87907?tab=description Verify your .dlls first. Also, get bass if you haven't  or use ba2 patcher https://www.nexusmods.com/fallout4/mods/82114, perhaps its an archive.

 

Otherwise, deactivate mods from the bottom up until the game starts.

[schwarzbrand]

The game was running for a while. Next day the game don't start anymore.

I tried to investigate, switching resolution, tried different ini versions, running direct in steam without MO2. Always the same. Screen goes black and the game-tab opens for one or two seconds, than back to desktop. On steam-startup I got an error code that some archives miss match - I guess normal for an downgraded version.

Reinstalled, NG-Version was running. Than downgraded again. Same failure at startup.

Here the CM-info. dll's , archives and modules everything fine. Although F4SE shows only supported dll's. 

 

At the moment I don't kno what to do. Deactivate mods wouldn't help, because in this early state there are no mods loaded.

[schwarzbrand]

When starting FO4 via the steam the game runs in the downgraded version. If I use MO2 und want to start via F4SE the game won't start anymore. All executables are started as Admin and my windows user profile is also registered as Admin.

Maybe I have to reset the whole MO2 installation. Deactivate latest installed mods didn't change anything.

[deff.]

4 hours ago, schwarzbrand said:

When starting FO4 via the steam the game runs in the downgraded version. If I use MO2 und want to start via F4SE the game won't start anymore. All executables are started as Admin and my windows user profile is also registered as Admin.

Maybe I have to reset the whole MO2 installation. Deactivate latest installed mods didn't change anything.

 

How did you downgrade game? Downloaded files from Steam via console or with downgrader?

 

First two mods are installed? 

 

Spoiler

 

[judge007]

9 hours ago, schwarzbrand said:

The game was running for a while. Next day the game don't start anymore.

I tried to investigate, switching resolution, tried different ini versions, running direct in steam without MO2. Always the same. Screen goes black and the game-tab opens for one or two seconds, than back to desktop. On steam-startup I got an error code that some archives miss match - I guess normal for an downgraded version.

Reinstalled, NG-Version was running. Than downgraded again. Same failure at startup.

Here the CM-info. dll's , archives and modules everything fine. Although F4SE shows only supported dll's. 

 

At the moment I don't kno what to do. Deactivate mods wouldn't help, because in this early state there are no mods loaded.

You have 37 Archives for NextGen installed, see the button that says "Archive Patcher"?

[schwarzbrand]

On 8/8/2026 at 6:36 AM, judge007 said:

You have 37 Archives for NextGen installed, see the button that says "Archive Patcher"?

Already done, that were mostly CC based content. No change in starting the game when patched correctly.

 

On 8/8/2026 at 4:34 AM, deff. said:

 

How did you downgrade game? Downloaded files from Steam via console or with downgrader?

 

First two mods are installed? 

 

  Reveal hidden contents

 

I used the FO4 downgrader from Nexus and downgraded via downloading archives. FO4 Downgrader

Yes, the required mods are installed as the very first in MO2.

It is a bit weired, after the first reinstall it was possible to start the game via F4SE and it loaded all mods, AFF was running. I could create my player character and walked to red-rocket. There I did a save and exited to desktop. Then I installed some additional overlays, one additional AFF animation and switched vom UAP to EAP. Nothing that would block the base game from starting. I can deactivate them but that dosn't have any effect in starting with MO2.

 

The "naked" reinstalled and downgraded FO4 is running - launched via the Fallout4-launcher. Starting it with F4SE via MO2 doesn't run and its producing always the log like in the first post. Only change in every log is the process code from the fallout.exe

[judge007]

1 hour ago, schwarzbrand said:

Already done, that were mostly CC based content. No change in starting the game when patched correctly.

 

 

Could you rerun CM Toolkit again, and post the screenshot of the "Overview" tab now that the archives are patched?

[schwarzbrand]

I tested some time today (using bethini pie for the ini files) and the game will now start through MO2 when usiung the Fallout.exe instead of F4SE. But than no F4SE based mods will be loaded. When starting through F4SE I'll now have the black loading screen for half an minute before crashing instead of a few seconds. And I recently got some crash logs now. Is that a problem caused by buffout???

 

crash-2026-08-09-19-46-18.log

 

 

[judge007]

3 hours ago, schwarzbrand said:

I tested some time today (using bethini pie for the ini files) and the game will now start through MO2 when usiung the Fallout.exe instead of F4SE. But than no F4SE based mods will be loaded. When starting through F4SE I'll now have the black loading screen for half an minute before crashing instead of a few seconds. And I recently got some crash logs now. Is that a problem caused by buffout???

 

crash-2026-08-09-19-46-18.log 40.62 kB · 0 downloads

 

 

 

 

In regards to the crash:

 

This is a startup crash — it happened only 18 seconds into the process, during UI initialization, specifically while the game was loading fonts.

What's happening

The crash occurs in this call chain:

Main::Init_UI_Systems → BSScaleformManager (constructor) → ParseFontConfig → SetupTextManager → DrawTextManager → AllocEntry [CRASH]

The game was in the middle of loading Interface\fonts_en.swf (visible on the stack at RSP+180) when it tried to write through a null pointer (RCX = 0x0) into Scaleform's rendering context table. In plain terms: the font/UI resource system tried to register a font entry into a table that doesn't exist yet — meaning something failed to initialize or load correctly just before this point, and the game didn't catch that failure before continuing.

Most likely cause

This pattern (null-pointer crash during Scaleform font setup at startup) is almost always caused by a broken or conflicting font configuration — most commonly from a UI-modifying mod. Looking at your load order, prime suspects are anything that touches fonts, interface swfs, or loads via fontconfig.txt:

ScreenArcherMenu, PipboyTabs, mcm (Mod Configuration Menu), XDI — all inject custom Scaleform/UI menus and can conflict over font registration

A missing or corrupted Interface\fonts_en.swf or fontconfig.txt (could be from a bad archive extraction, missing loose file, or overwritten Interface files)

Load order conflict where two mods try to define overlapping font entries

What I'd try, in order

Verify game files / re-extract Interface.ba2 — confirm fonts_en.swf and fontconfig.txt in your Data\Interface folder aren't corrupted or from a mismatched version.

Check for mods that install Interface\fontconfig.txt (MCM, PipboyTabs, and several UI mods do this) — if two mods both ship a modified fontconfig.txt, whichever loads last "wins" and can produce malformed entries if incompatible. Use a mod manager conflict checker to see if anything is overwriting it unexpectedly.

Temporarily disable ScreenArcherMenu, PipboyTabs, and MCM one at a time and relaunch — since they're the most likely to inject custom Scaleform UI elements — to isolate which one (if any) is responsible.

Check Buffout4's crash log settings — since Buffout4 is installed, its own generated log (in Documents\My Games\Fallout4\F4SE\Crash Logs) may have a cleaner "PROBABLE CALL STACK" with named plugin culprits, since Buffout4 does better symbol resolution than this Addictol log for some cases.

 

 

Other than what AI suggested above, I can only suggest to reinstall F4SE and try again

Do you have Addictol AND Buffout 4 installed?

[Samhsay]

7 minutes ago, judge007 said:

Addictol

For some reason, Addictol was causing my game to crash. I didn't bother troubleshooting it and switched back to Buffout, but the crash log was similar.

[judge007]

6 minutes ago, Samhsay said:

For some reason, Addictol was causing my game to crash. I didn't bother troubleshooting it and switched back to Buffout, but the crash log was similar.

Are you also @schwarzbrand?

[Samhsay]

8 minutes ago, judge007 said:

Are you also @schwarzbrand?

Okay, no one can speculate about the source of the problem in the thread.

[schwarzbrand]

9 hours ago, judge007 said:

 

In regards to the crash:

 

  Hide contents

 

 

 

This is a startup crash — it happened only 18 seconds into the process, during UI initialization, specifically while the game was loading fonts.

What's happening

The crash occurs in this call chain:

Main::Init_UI_Systems → BSScaleformManager (constructor) → ParseFontConfig → SetupTextManager → DrawTextManager → AllocEntry [CRASH]

The game was in the middle of loading Interface\fonts_en.swf (visible on the stack at RSP+180) when it tried to write through a null pointer (RCX = 0x0) into Scaleform's rendering context table. In plain terms: the font/UI resource system tried to register a font entry into a table that doesn't exist yet — meaning something failed to initialize or load correctly just before this point, and the game didn't catch that failure before continuing.

Most likely cause

This pattern (null-pointer crash during Scaleform font setup at startup) is almost always caused by a broken or conflicting font configuration — most commonly from a UI-modifying mod. Looking at your load order, prime suspects are anything that touches fonts, interface swfs, or loads via fontconfig.txt:

ScreenArcherMenu, PipboyTabs, mcm (Mod Configuration Menu), XDI — all inject custom Scaleform/UI menus and can conflict over font registration

A missing or corrupted Interface\fonts_en.swf or fontconfig.txt (could be from a bad archive extraction, missing loose file, or overwritten Interface files)

Load order conflict where two mods try to define overlapping font entries

What I'd try, in order

Verify game files / re-extract Interface.ba2 — confirm fonts_en.swf and fontconfig.txt in your Data\Interface folder aren't corrupted or from a mismatched version.

Check for mods that install Interface\fontconfig.txt (MCM, PipboyTabs, and several UI mods do this) — if two mods both ship a modified fontconfig.txt, whichever loads last "wins" and can produce malformed entries if incompatible. Use a mod manager conflict checker to see if anything is overwriting it unexpectedly.

Temporarily disable ScreenArcherMenu, PipboyTabs, and MCM one at a time and relaunch — since they're the most likely to inject custom Scaleform UI elements — to isolate which one (if any) is responsible.

Check Buffout4's crash log settings — since Buffout4 is installed, its own generated log (in Documents\My Games\Fallout4\F4SE\Crash Logs) may have a cleaner "PROBABLE CALL STACK" with named plugin culprits, since Buffout4 does better symbol resolution than this Addictol log for some cases.

 
 

 

 

 

Other than what AI suggested above, I can only suggest to reinstall F4SE and try again

Do you have Addictol AND Buffout 4 installed?

Yes, I've both installed. I thought buffout is an requirement for addictol - I'll disabled buffout but without any change. The whole UI installation is like in Fallout for Beginners guide. I look later if there is an buffout crash log.

 

8 hours ago, judge007 said:

Are you also @schwarzbrand?

Nope. I'm the one and only.

 

 

[judge007]

6 hours ago, schwarzbrand said:

Yes, I've both installed. I thought buffout is an requirement for addictol - I'll disabled buffout but without any change. The whole UI installation is like in Fallout for Beginners guide. I look later if there is an buffout crash log.

 

Nope. I'm the one and only.

 

 

https://themidnightride.moddinglinked.com/intro.html
https://stepmodifications.org/wiki/Fallout4:1.0

Modding 101 https://www.nexusmods.com/fallout4/articles/2006
Fallout 4 Mod List and Load Order Guide https://www.nexusmods.com/fallout4/mods/23556

 

Excellent guides on using Mod Organizer 2 and Vortex are located on AAF Discord.
{Link to AAF Discord site is located in @dagobaking 's signature in any of his posts}

 

https://www.loverslab.com/topic/139374-aaf-the-fucking-manual-~-adult-oriented-setup-guide-~-30june2026/

[schwarzbrand]

Removing Buffout no change. Game still doesn't start.

Reinstalled it.

Removing ADDICTOL was the clue. Game is running again.

 

I remembered that I installed Addictol because it was an Mod Requirement - but the mod runs now without it. Learning by doing, and from "a quick new mod install" I had the worst case of an not starting game. Thanks for your help.

 

@judge007: thanks for links. I knew only the midnightride guide or the guides for Fallout and AAF here in the forum.