Hi,
There is a problem loading the Topography World Hillshade. When I open a existing web map or a new empty map. I got this error below.
I met same problems on Wednesday for one of my layer, I copied the data from this layer and uploaded it as a new weblayer and then the problem seems gone and I can't reproduce this error again. I don't know why this happens but I assume the error is not on your site. I would advise that you open the web map from some other web layers you have and delete things that maybe related to it and try again, otherwise, I recommand you contact Esri.
Hi @ZiqingYu,
it was resolved the next day. probably some basemap layer/server issue