Issue with Text Mesh

Hello.

I've got a problem recently when override void OnPopluateMesh. Sometime it print this two errors: 1.Mesh.uv3 is out of bounds.The supplied array needs to be the same size as the Mesh.vertices array UnityEngine.Canvas:SendWillRenderCanvases()

2.Mesh.uv4 is out of bounds.The supplied array needs to be the same size as the Mesh.vertices array UnityEngine.Canvas:SendWillRenderCanvases()

This doesn't happen very often.

When this happens, the text mesh's uv becomes chaos. And this uv problem get right when ui rebuild(I am not sure, but the uv will get right when ui change something ).

I don't know how this problem arose.

Does anybody have any idea about this?

Thank you very much!

Version of Unity: 5.6.3f1 (64-bit)

Here is my code:

 protected override void OnPopulateMesh(VertexHelper toFill)
 {
     if (null == font) return;
     m_DisableFontTextureRebuiltCallback = true;
     Vector2 extents = rectTransform.rect.size;
     var settings = GetGenerationSettings(extents);
     cachedTextGenerator.PopulateWithErrors(text, settings, gameObject);
     IList<UIVertex> verts = cachedTextGenerator.verts;
     float unitsPerPixel = 1 / pixelsPerUnit;
     int charCount = (verts.Count - 4) / 4;
     Vector2 roundingOffset = new Vector2(verts[0].position.x, verts[0].position.y) * unitsPerPixel;
     roundingOffset = PixelAdjustPoint(roundingOffset) - roundingOffset;
     Debug.Log("Populate111");
     toFill.Clear();
 
     UILineInfo[] uiLineInfos = cachedTextGenerator.GetLinesArray();
     ClearLinksBoxs();
     Debug.Log("Populate222");
     InitUnderlineV4();
     Debug.Log("Populate333");
     UpdateEmojis(verts, charCount, uiLineInfos);
     for (int i = 0; i < charCount; i++)
     {
         UIVertex[] charVerts = TextUtil.GetCharVs(verts, i, 4);
         for (int j = 0; j < charVerts.Length; j++)
             charVerts[j].position *= unitsPerPixel;
         if (roundingOffset != Vector2.zero)
             TextUtil.AddOffset(charVerts, new Vector3(roundingOffset.x, roundingOffset.y, 0));
         ELink elink = GetELink(i);
         if (null != elink)
         {
             if (null != elink.data.color)
                 TextUtil.SetColor(charVerts, elink.data.color);
             if (elink.data.interactable)
                 elink.AddBox(charVerts[3].position, TextUtil.GetSize(charVerts));
         }
         if (IfshowEmojiSpr(i))
             TextUtil.ClearUV(charVerts);
         toFill.AddUIVertexQuad(charVerts);
     }
     Debug.Log("Populate444");
     UIVertex[] linesVs = GetLinesVerts(verts, uiLineInfos);
     int lineCount = linesVs.Length / 4;
     Debug.Log("lineCount: " + lineCount);
     for (int i = 0; i < lineCount; i++)
         toFill.AddUIVertexQuad(TextUtil.GetCharVs(linesVs, i, 4));
     Debug.Log("Populate555");
     m_DisableFontTextureRebuiltCallback = false;
     meshPoped = true;
     Debug.Log("Populate666");
 }

When this problem show up, it start with "Populate333"...