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Troubleshooting and FAQ

Installation and startup​

Plugin was built for a different engine version​

Close Unreal, replace the plugin with the exact UE 5.5/5.6/5.7/5.8 package, and remove stale copied packages from other project plugin locations. Do not copy only DLLs between builds.

The plugin or SA nodes are missing​

Enable Spline Architect and its dependencies, then restart. Streets Network, Lot Zone, Streets Mode, and the SA PCG nodes exist only in the UE 5.8 package — they are absent from the 5.5, 5.6, and 5.7 archives, so a missing Streets Network actor on an older engine is expected, not a broken install. See compatibility.

Actor generation​

The Preset Library is empty​

The plugin includes starter presets for Walls, Buildings, Curves and Custom Pieces. An empty library is not the expected starting point.

Clear the search text, turn off Favorites filtering, and select the matching category. The category and Favorites filter are remembered between sessions.

If the presets are still missing, check that your installed plugin includes the SA_Walls, SA_Buildings, SA_Curves and SA_CustomPieces DataTables in its Content/Presets folder. These ship with the UE 5.5–5.8 packages. If the files are missing, reinstall the complete package for your engine version using the installation guide.

If the presets are visible but a newly placed actor starts empty, check its default preset under Project Settings → Plugins → Spline Architect Settings. Existing projects can override the starter defaults. Changing a default affects new actors; assign a preset directly to an actor that is already in the level.

A Wall is empty​

  • Assign a valid Wall Mesh or Custom Wall Mesh.
  • Confirm the DataTable uses the WallPreset row structure and the row still exists.
  • Check Skip Pieces, Custom Piece gaps, knockout, and Booleans.
  • Make the spline long enough for the logical Wall Length, or add shorter/filler pieces.
  • Force Regenerate after fixing an asset reference.

Corners have gaps or spikes​

  • Verify mesh bounds and pivot, then correct Corner Length/Height Add.
  • Add small Overlap Pieces/Overlap Corners values.
  • Remove near-duplicate path points or increase Collapse Nearby Spline Point Distance.
  • Use the corner type that matches the asset: Straight, Bend, Chamfer, or Pipe.
  • Prebake the actual angles and choose a sensible Corner Angle Increment.

The actor changes every rebuild​

Set a non-negative Seed. A -1 seed resolves once to a concrete value, but duplicated/imported legacy actors should still be inspected and saved with an explicit resolved seed when exact reproducibility matters.

A spline command skipped my actor​

Close/Open, Gridify, Flatten, Reverse, Mirror, and Apply Shape refuse to guess when an actor has more than one spline, and tell you which actors they skipped. Select the spline component in the level editor, or pick a point on the path in Architect Mode, then run the command again. Actors with a single spline are unaffected.

A transformed actor behaves strangely​

Use Reset Transform or keep Auto Normalize Actor Scale enabled. Avoid leaving non-unit scale on spline-driven actors; bake it into points instead.

Floors, roofs, and Booleans​

Floor/roof is missing​

Close the spline, fix self-intersections, reduce inset, and remove near-duplicate corners. A roof slope inset larger than the viable polygon can collapse the result.

Boolean has no effect​

Make the cutter overlap in 3D, increase Spline Extrude Distance, enable the correct Affect toggles, and confirm Target Actors is not overriding Auto Detect. Cull removes whole components; Boolean Subtract cuts their geometry.

Baking and output​

A change unbaked my actor​

That is expected. Spline Architect prevents stale persistent output after authored edits. Inspect the regenerated result and run Bake/Rebake Connected.

Too many components or draw calls​

Use Instanced or Hierarchical Instanced bake/output, consolidate compatible meshes/materials, and check that small material differences are not breaking instance groups.

Baked lighting is poor​

Enable generated lightmap UVs, set an appropriate texel density, inspect the destination UV channel, and use the Lightmap Tool for source assets. Confirm Static mobility and rebuild lighting.

Conversion lost output​

Enable Bake Spline Architect Actors Before Convert, include attached actors where needed, and wire/realize Dynamic Mesh output before expecting non-static surface pieces in a PCG Data workflow. Keep originals until validation passes.

PCG​

See the node failure table. Also confirm sa.PCGAutoRefresh remains at its default 1; setting it to 0 intentionally requires manual PCG regeneration after SA edits.

Performance​

  • Increase edit debounce if slider scrubbing triggers excessive work.
  • Lower the interactive task budget if viewport hitches matter more than completion time.
  • Increase the idle budget to drain queued generation faster after input stops.
  • Reduce surface density, smoothing iterations, roof resolution, and PCG sample counts before changing architecture.
  • Use Debug (Skeleton Only) while editing a large Streets graph.

Where is MultiBuilding or Prop Spawner?​

They were removed from the v6 authoring surface. Their scalable replacement is the UE 5.8 PCG workflow: Streets lots + SA Subdivide Lots + SA Spawn Building for city parcels, and Edge Placer / Surface Sampler + Pick From Pool for props. See migration.