"Error occurred while loading this layer" in Experience Builder Developement Edition

Question

I am facing issues with the ExB developer edition. All the layers in the map doesn't load and in map Layer Widget we see an error: "Error occurred while loading this layer" .

The same web map loads in Map viewer and even loads in ExB created through portal. However, it doesn't work in dev edition.

GeeteshSingh07 · Answer

@Allen_Zhang , thank you for the help. it was internal CORS issue resolved by our IT by adding CORS to header or something

Allen_Zhang · Answer

Not sure if this is your case, but I found a similar post: https://community.esri.com/t5/arcgis-online-questions/existing-layers-showing-quot-error-occurred/td-p/1191853

More details would help locate the problem.