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Won't Fix

Votes

1

Found in [Package]

4.2.0

5.0.0-pre.1

Issue ID

FBX-437

Regression

No

FBX Exporter throws a KeyNotFoundException when exporting a high-polygon mesh

Package: FBX Exporter

-

Reproduction steps:

  1. Open the attached “TempFBXExportRepro” project
  2. Open the “SampleScene” scene
  3. In the Hierarchy right-click on “DoesNotExport” GameObject
  4. In the context menu select “Export To FBX…”

Expected result: No errors in the Console
Actual result: Export is unsuccessful, error in the Console

Reproducible with: 4.2.0, 5.0.0-pre.1 (2020.3.42f1, 2021.3.15f1, 2022.1.24f1, 2022.2.1f1, 2023.1.0a22)

Reproduced on: Windows 10

Part of the error:
KeyNotFoundException: The given key '(NaN, NaN, NaN)' was not present in the dictionary.
System.Collections.Generic.Dictionary`2[TKey,TValue].get_Item (TKey key) (at <d6232873609549b8a045fa15811a5bd3>:0)
UnityEditor.Formats.Fbx.Exporter.ModelExporter.ExportMesh (UnityEditor.Formats.Fbx.Exporter.ModelExporter+MeshInfo meshInfo, Autodesk.Fbx.FbxNode fbxNode) (at Library/PackageCache/com.unity.formats.fbx@4.1.2/Editor/FbxExporter.cs:892)

  1. Resolution Note:

    Closing this bug as first it is very old and unlikely to still be a problem.
    Also, looking at the code, this looks like a faulty input mesh asset that contains NaN values.

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Comments (2)

  1. danielpatyk

    Jul 15, 2025 11:24

    Is it a problem to apply the mentioned fix from the comments?

  2. rachid_bouemama

    Feb 16, 2025 08:41

    #look for this method
    bool ExportMesh(MeshInfo meshInfo, FbxNode fbxNode)
    {
    ...
    #inside this loop
    foreach (int val in vertOrder)
    {
    int polyVert = indices[polySize * f + val];

    #Add this :

    // Check for NaN values before attempting to access the dictionary
    if (float.IsNaN(meshInfo.Vertices[polyVert].x) || float.IsNaN(meshInfo.Vertices[polyVert].y) || float.IsNaN(meshInfo.Vertices[polyVert].z))
    {
    continue; // Skip this iteration if NaN is found
    }
    #End Fix
    #rest code..
    unmergedPolygons.Add(polyVert);

    polyVert = ControlPointToIndex[meshInfo.Vertices[polyVert]];
    fbxMesh.AddPolygon(polyVert);
    ...
    }}

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