Firefox 17 ESR Support

After the upgrading to b21, I'm getting a WebGL error when I try to load the Cesium demo on the main page at It says:

An error occurred while rendering. Rendering has stopped.

RangeError: invalid array length

I'm running Firefox ESR 17.0.9 on Windows 7 with an NVIDIA NVS 4200M graphics card, driver dated 2-22-2013. Any ideas on what the problem may be? I've had issues with Cesium running on versions of Firefox older than the ESR before (which I expected), but this is the first time I've had an issue using the latest ESR release.


Firefox 17 ESR is about to be end-of-life and Firefox 24 is the latest ESR release. I would recommend switching to that.

The second thing to try would be to update your video card driver, which is about 7-8 months out of date.

If you can’t do either of those things, there’s not much we can recommend at this time, other than to go back to b20 and see if it works. By the time b22 comes out, I believe 17esr will be unsupported by Mozilla.

I installed the 17 ESR and I see the same error in CesiumViewer. Surprisingly, there’s only one test failure:

Core/TaskProcessor can transfer array buffer. (show summary)

Expected 100 to equal 0.

Not sure if this is the cause of the problems. I also see these errors in CesiumViewer:

[13:35:26.578] Error: WebGL: clear: incomplete framebuffer @ http://localhost:8080/Source/Renderer/Context.js:2038

[13:35:26.578] Error: WebGL: drawArrays: incomplete framebuffer @ http://localhost:8080/Source/Renderer/Context.js:2188

This looks more like renderer-level problems which might be the culprit.

To follow up on this, I was able to track down the problem and we just merged a fix for FF17 into master that will be part of b22.

You can hotfix b21 if you need to by manually applying this one-line change to CesiumWidget:


Thank you, that is great news. We’ll apply the patch!