Bug located in load state on linux #122

🐞 Description of the bug

When loading a state from an empty scene in a Linux environment, the visualizer gets into a broken state, not fixable by a refresh or a new API call.

The viewer does not display the new dataset in the canvas, though the UI elements are responsive and seem to contain the correct info (e.g. the tree view hierarchy and the part properties panel). A refresh does not restore the dataset in the canvas.

The uncaught exception message reads Exception {message: Array(2), stack: 'Error: std::bad_alloc,std::bad_alloc\n at ___thr…tkWebAssembly.wasm:wasm-function[37703]:0x1c82765'}

Oher times we see the geometry partially rendered, or rendered wrong:

Notes:

• This behaviour works as expected on Windows. It shows the error behaviour on a Linux system, and on a Docker container on a Windows system.
• Was exposed when a regression test started failing, but upon further investigation that test seems to have been passing despite the canvas being empty on linux.
• The described behaviour on linux has been reproduced on linux tracing back to Mar 2026 (or further) in the old internal repo: e.g. on c34ebb92dbca1cb876612686194be22a92d848b2.
• The bug was found when running load_state into an empty scene, which also loads a dataset. To make sure this doesn't also affect add_dataset, tested running add_dataset from an empty scene on the VISOR main branch, in the python3.11 dev docker container. It succeeded. The bug is isolated to load_state.

📝 Steps to reproduce

Two options: Linux environment, or use the dev docker container (on any environment, e.g. Windows). The reproduction for both is the same, except that the way the service is run is different. The two options for running the service are outlined here; the reproduction is in the next section and is the same for both.

1. Running the VISOR service

a. Linux environment

> visor-cli server start

b. VISOR dev docker container

docker compose -f deploy/docker/dev/docker-compose.yml up --build

This will run the VISOR service on the same default port as the CLI command above.

2. Reproduction

a. Prerequisite: save a state from a VISOR scene.

> visor-cli instance start examples/assets/vtk_scene_sphere_l2_b3_r32_v3_c1_z0.vtm
# adjust camera/part properties etc>
> visor-cli instance save saved1
# directory saved1 contains the `visor.json` file and the cached dataset

b. Start a VISOR visualizer with an empty scene, and load the saved state

* visor-cli instance start
* visor-cli instance load saved1

📦 Installed packages and configuration

Tested on the following configurations:

1. Windows with docker container
2. Linux

🚦 Defines the severity of the bug. In the case of class-3, specific information must be added.

Class 1 - Crash/Major data loss

📦 Support ticket ID

No response

🐞 Found in

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🩹 Fixed in

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Root cause

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Third Party

• This bug is introduced by a third party

Released Bug

• This bug is in a released product