Failed to load resource error

Please help me.
In my application, the camera will not move until viewer.scene.globe.tilesLoaded become true.
But sometimes I will get an error:
Failed to load resource: net:: ERR_TIMED_OUT
The resource could be terrain.

And then the camera will just be stuck there.

Here is my question:

1.I wonder if cesium is going to reload the terrain resource?

2.How can I manually trigger Cesium to reload the terrain resource?

3.Is there any event when it failed to load terrain resource?

Thanks!

How often does this happen? Are you loading the default terrain from ion?

Are you getting like an error message that pops up? If so, could you post the full error here? If you get an error in the browser console that would be helpful to see here too.