Client crash (EXCEPTION_ACCESS_VIOLATION) preceded by continuous 'fort.input.upgrades.movement' CVar warning spam

General Issues and Bug Reporting
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Summary

During UEFN playtest sessions, the Fortnite Creative client repeatedly crashes with EXCEPTION_ACCESS_VIOLATION (read and write variants seen). Every crash is preceded by a massive per-frame spam (100k-160k+ lines per session) in the log:

LogBlueprintUserMessages: Warning: Failed to find console variable ‘fort.input.upgrades.movement’.

logged roughly twice per frame, continuously, for the entire session. Immediately before each crash there is also a ~300ms game-thread hitch tied to RenderVirtualShadowMaps(Non-Nanite), followed by the fatal exception on the render/worker thread.

We confirmed this is not caused by our own project content: the string ‘fort.input.upgrades.movement’ does not appear anywhere in our project’s Verse source or in any of our project’s own Blueprint/uasset files. The spam is present across multiple separate sessions over 3 days (Sept 8-10, 2026), so it is not a regression from anything we changed - it looks like a pre-existing engine/native issue querying a console variable that no longer exists in this build.

Please select what you are reporting on:

Unreal Editor for Fortnite

What Type of Bug are you experiencing?

Stability

Steps to Reproduce

  1. Open a UEFN project and launch a Play-in-Fortnite / playtest session
  2. Check the client log (FortniteGame.log) during the session - the ‘Failed to find console variable fort.input.upgrades.movement’ warning starts appearing almost immediately and repeats continuously (roughly 2x per frame) for the whole session
  3. Keep the session running for an extended period (tens of minutes)
  4. Eventually the client crashes with EXCEPTION_ACCESS_VIOLATION, always preceded by a ~300ms hitch on RenderVirtualShadowMaps(Non-Nanite)

Expected Result

The console variable ‘fort.input.upgrades.movement’ should either exist in this build or not be queried at all - no per-frame warning spam, and no resulting client crash during normal playtest sessions.

Observed Result

The client crashes with EXCEPTION_ACCESS_VIOLATION (both read and write address variants observed) after a period of active play. The FortniteGame.log shows continuous spam of “LogBlueprintUserMessages: Warning: Failed to find console variable ‘fort.input.upgrades.movement’.” (154k-163k occurrences across sessions) starting near session start, plus a ~300ms hitch on RenderVirtualShadowMaps(Non-Nanite) immediately before each crash. Verified this is not from our own project content (no match for that string anywhere in our Verse/Blueprint assets), and it also appears in log backups from prior sessions over the last 3 days.

Platform(s)

PC (Windows) - UEFN editor Play-in-Fortnite / playtest client

Additional Notes

Confirmed the CVar string does not appear anywhere in our own project’s Verse or Blueprint content, so this looks like a native/engine-side lookup. Happy to share full log excerpts (FortniteGame.log / UnrealEditorFortnite.log) if that helps investigation.

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Thanks for reporting this, I’ve sent this in directly

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Hi @GG-Gaming,

Please could you send me your logs & island code. This seems to be tied to your project
You are welcome to DM it to me if needed

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Hi Rhyan, thanks for looking into this.

I’ll send you the island code via DM (it’s a private/unpublished version I’m using to isolate the issue).

Here’s a small log sample rather than the full file (49,814 occurrences of the warning in this one session alone).

[2026.09.10-08.21.32:142][594]LogBlueprintUserMessages: Warning: Failed to find console variable 'fort.input.upgrades.movement'.

[2026.09.10-08.21.32:159][595]LogBlueprintUserMessages: Warning: Failed to find console variable 'fort.input.upgrades.movement'.

...

[2026.09.10-08.21.33:044][598]LogCore: Error: Hitch detected on gamethread, frame hasn't finished for 304.04ms.

[2026.09.10-08.21.33:046][598]LogWindows: Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffffffffffff

Happy to send the full FortniteGame.log (or the specific backup file covering this crash) via DM if useful.

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Got two more crashes today with the identical signature (EXCEPTION_ACCESS_VIOLATION, null read), plus a repro pattern that might help triage.

  1. Both times the crash happened 1-2 seconds after a fullscreen custom Verse UI (opened via AddUIWithInput, wrapped in UEFN’s “PushPrimaryContent_UEFN_VerseActivableWidgetBase” scene) was closed/torn down (LogDynamicUI: “Removing scene…”, input mode Menu to Game).

  2. Second occurrence: crash triggered right after clicking Claim on a Daily Reward UI. That click closes the fullscreen scene and immediately opens a second small popup widget (via PlayerUI.AddWidget, InputMode.None) to show the reward. The crash lands right as that second widget is being added, within about 1 second of the first scene’s teardown.

  3. The continuous “fort.input.upgrades.movement” CVar spam was present for the whole session (over an hour, roughly 50 to 60 messages per second) both times, not something that only started right before the crash. Looks like ambient noise rather than the direct trigger, but present in every run that eventually crashed.

  4. Engine version: 6.0.0-57819926+++Fortnite+Release-42.10

GameStateName: Playspace_GameState_C

  1. No Verse-level error or warning appears in the log at the crash point, the client log just stops mid-spam.

This points more toward a race in the scene teardown path (RemoveUI or scene pop on a fullscreen Verse-driven UI) when another widget gets added very shortly after, rather than something actionable from our Verse code. Happy to share the full crash logs and minidumps if that helps.

1 Like
8

Thank you, I’ll relay this back to the QA team

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FORT-1151116 is ‘Closed’ as ‘Fixed’. The issue will be addressed in 42.20.

1 Like