glGenSyncTokenCHROMIUM exception randomly thrown


I observed (and also had it reported by some of my users) the following exception leading to Cesium crashing.

It happens very randomly, sometimes after of a long period of normal operation of Cesium (one hour+)

Here is the log:

GL_INVALID_OPERATION : glGenSyncTokenCHROMIUM: fence sync must be flushed before generating sync token

WebGL: CONTEXT_LOST_WEBGL: loseContext: context lost

Cesium.js:477 An error occurred while rendering. Rendering has stopped.


RangeError: Invalid array length

RangeError: Invalid array length

at ye (

at Se (

at Ve (

at Be (

at qe (

at de.render (

at P.render (

at t (

This is Cesium 1.27 stable, running on Google Chrome (54.0.2840.99 m (64-bit)) with a Geforce 610M

It has been reported to me that this error does not occur when running on Firefox but I can not confirm this.



Thanks Xavier. Do you have any way for us to reproduce this? It will be very difficult for us to figure out what is going on otherwise.



Hi Hannah,

Sadly, I do not have any reproductible scenario: this appears to be quite a rare and random error.

I just thought I would let you know in case the logs and error message would ring any bell.



Did you ever figure out what was causing this?

Apparently this issues was resolved by reducing the tile cache size I had pushed to unreasonable value. Vram would eventually fill up and that would cause the crash after some time.

This is not entirely confirmed yet but it looks promising.