Python Editor Scripting doesn't initialize in 41.20 despite being enabled in Project Settings

General Issues and Bug Reporting
1

Summary

Python Editor Scripting will not initialize in UEFN 41.20 even though it’s enabled in
Project Settings. Tools → Execute Python Script never appears, and every editor
session logs LogPython: Python disabled via CVar ‘Engine.Python.IsEnabledByDefault’
with no Python activity afterward. I’m trying to use editor-side Python for
repetitive level work (bulk actor placement and transforms, asset import and organization) the setup passes I currently redo by hand on every map. Gameplay logic stays in Verse; this is purely editor automation.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Assets

Steps to Reproduce

  1. Open a project in UEFN 41.20 (CL-55550516)
  2. Go to Project Settings, search “Python”, and enable Python Editor Scripting
  3. Close and reopen the project
  4. Open the Tools menu and look for “Execute Python Script”
  5. Check UnrealEditorFortnite.log for LogPython entries

Expected Result

Python initializes at editor startup and “Execute Python Script” appears in the Tools menu, as described in the “Python Tools in UEFN” documentation.

Observed Result

Python never initializes. The log shows only LogPython: Python disabled via CVar
‘Engine.Python.IsEnabledByDefault’ and no further Python activity. “Execute Python Script” never appears in the Tools menu.

Platform(s)

Windows 11 (PC)

Additional Notes

  • The per-project local enable does persist — EnablePythonLocallyPerProject=True for
    each project ID in EditorPerProjectUserSettings.ini
  • Reproduced on three separate projects, including new ones, so it isn’t
    project-specific corruption
  • Toggling the checkbox writes no corresponding key to the .uplugin or .uefnproject
    (Scene Graph writes “EnableSceneGraph”: true by comparison)
  • The editor sets Engine.Python.IsPythonLifeCycleDynamic=1 at startup, but nothing
    triggers Python to initialize
  • The Output Log console offers no Cmd input mode in my build, so py commands can’t be run manually
  • Engine.Python.IsEnabledByDefault=1 in a user-level Engine.ini is removed by the
    editor at startup; the same override in the project’s Config/DefaultEngine.ini has no effect.

I’ve read conflicting ideas on if it is gated or not. If it is gated, could I please have access?

2

Confirming this on 41.20 — reproduces cleanly, looks like a regression.

Same symptom here on Fortnite Ecosystem 41.20 (released 2026-07-16), UEFN on Windows 11. Python Editor Scripting will not initialize even though it’s enabled for the project.

What’s enabled (so this isn’t a “did you turn it on” case):

  • Tools → (search “python”) → “Enable Python locally for this project” is checked.
  • The project’s GUID is present as True in EnablePythonLocallyPerProject under [/Script/UnrealEd.EditorPerProjectUserSettings] in EditorPerProjectUserSettings.ini.

What actually happens at startup (from UnrealEditorFortnite.log):
LogConfig: Set CVar [[Engine.Python.IsPythonLifeCycleDynamic:1]]
LogPython: Python disabled via CVar ‘Engine.Python.IsEnabledByDefault’
That is the only LogPython line for the entire session — no interpreter init, no version banner, nothing after it. Consistent with the interpreter never starting.

Consequences:

  • No Tools/File → Execute Python Script item.
  • No command input at the bottom of the Output Log (and no Cmd/Python mode selector).
  • No in-viewport (~) console.

Things I tried that did NOT help:

  • Toggling the “Enable Python” checkbox off/on in-session — no interpreter start, no new LogPython activity.
  • Setting Engine.Python.IsEnabledByDefault=1 under [ConsoleVariables] in the per-user …\Saved\Config\WindowsEditor\Engine.ini — UEFN deletes/regenerates that file on launch, so it has no effect. (Others in the 41.20 threads report the project-level edit is ineffective too.)
  • UE_PYTHONPATH autostart / init_unreal.py — never runs, since Python never initializes.

Why this looks like a 41.20 regression: UEFN Python Editor Scripting worked on earlier builds (e.g., community MIT UEFN Python listeners published back in March 2026). It only stopped for me on 41.20.

Questions for Epic:

  1. Is this a known 41.20 regression, and is a hotfix planned?
  2. For accounts that already have the “Enable Python” checkbox, is there any additional required step, or is the dynamic interpreter start simply broken in 41.20?

Here is my full UnrealEditorFortnite.log if useful.

UnrealEditorFortnite.log (1.4 MB)