# vtk wasm script error not a VtkRenderWindow

**URL:** https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076
**Category:** vtk.wasm
**Tags:** pyvista, python
**Created:** [October 1, 2025, 2:38pm UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076 "2025-10-01T14:38:28Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![jtristanod3d](https://discourse.vtk.org/user_avatar/discourse.vtk.org/jtristanod3d/32/10299_2.png) [@jtristanod3d](https://discourse.vtk.org/u/jtristanod3d)
#### Post date: [October 1, 2025, 2:38pm UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076/1 "2025-10-01T14:38:29Z")

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Wether using samples or my own apps, I get this console error. Is this something I need to be worried about?

2025-10-01 10:35:33.062 ( 0.039s) [7F5534] vtkSession.cxx:290 ERR| Object null at id=1is not a vtkRenderWindow!  
Is.console.error @ index-5f6ebc8d.js:23  
put\_char @ vtkWebAssembly.mjs:7  
write @ vtkWebAssembly.mjs:7  
write @ vtkWebAssembly.mjs:7  
doWritev @ vtkWebAssembly.mjs:7  
\_fd\_write @ vtkWebAssembly.mjs:7  
$func19152 @ vtkWebAssembly.wasm:0x1099807  
$func7265 @ vtkWebAssembly.wasm:0x56c1f3  
$func9801 @ vtkWebAssembly.wasm:0x6bb4cc  
$func5464 @ vtkWebAssembly.wasm:0x454ad3  
$func4081 @ vtkWebAssembly.wasm:0x383a66  
$func9843 @ vtkWebAssembly.wasm:0x6c0aef  
$func223 @ vtkWebAssembly.wasm:0x513ec  
$func50539 @ vtkWebAssembly.wasm:0x270473d  
$func47366 @ vtkWebAssembly.wasm:0x24bcad2  
dynCall @ vtkWebAssembly.mjs:7  
(anonymous) @ vtkWebAssembly.mjs:7  
vtkRemoteSession.setSize @ VM396:8  
setSize @ trame\_vtklocal.umd.js:1  
z @ trame\_vtklocal.umd.js:1

 ![image](https://discourse.vtk.org/uploads/default/original/2X/4/4e60a887281ab4d0372843ac80ce0db571674ea7.png)

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<div class="post-metadata">

### Author: ![Joe\_Tristano](https://discourse.vtk.org/user_avatar/discourse.vtk.org/joe_tristano/32/10300_2.png) [@Joe\_Tristano](https://discourse.vtk.org/u/Joe_Tristano)
#### Post date: [October 8, 2025, 10:05am UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076/2 "2025-10-08T10:05:14Z")

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i fixed this by creating a propper vtk pipeline

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<div class="post-metadata">

### Author: ![Joe\_Tristano](https://discourse.vtk.org/user_avatar/discourse.vtk.org/joe_tristano/32/10300_2.png) [@Joe\_Tristano](https://discourse.vtk.org/u/Joe_Tristano)
#### Post date: [October 8, 2025, 10:05am UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076/3 "2025-10-08T10:05:48Z")

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I still get the error but wasm says its using webgl

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<div class="post-metadata">

### Author: ![jaswantp](https://discourse.vtk.org/user_avatar/discourse.vtk.org/jaswantp/32/10046_2.png) [@jaswantp](https://discourse.vtk.org/u/jaswantp)
#### Post date: [October 8, 2025, 12:27pm UTC](https://discourse.vtk.org/t/vtk-wasm-script-error-not-a-vtkrenderwindow/16076/4 "2025-10-08T12:27:30Z")

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no need to worry about this.