The basemap gallery is empty in Portal for ArcGIS Map Viewer

Description

When attempting to change the basemap in Portal for ArcGIS Map Viewer, the basemap gallery displays a blank window with the message, ‘No content available.’, as shown in the following image.

Cause

The known causes for this issue are as follows:

• The Esri default basemap is not selected as the basemap gallery. 
• The Featured Maps and Apps group or a custom group without any basemap is selected as the basemap gallery.
• The browsing cache on the machine is not cleared.

Solution or Workaround

Depending on the cause, use one of the following options to resolve this issue.

Note:
Only an organization's default administrator or a custom role with administrative privileges can perform the following workflows.

Ensure the Esri default basemap gallery is selected

1. Log in to Portal for ArcGIS. Click Organization > Settings > Map.
2. Under Basemap Gallery, click the drop-down menu, and select Default.
   
    
3. On the top-left corner, click Save.

Ensure the custom or Featured Maps and Apps group contains basemaps
Share the Esri default basemaps to the custom or Featured Maps and Apps group.

1. Log in to Portal for ArcGIS. Click Organization > Settings > Map. 
2. Under Basemap Gallery, ensure the custom or Featured Maps and Apps group is selected.
3. Check the Share the Esri default basemaps to this group when you click Save. check box, and select Raster Basemaps or Vector Basemaps to share the Esri default basemaps.
   
   
    
4. On the top-left corner, click Save.

The image below shows the Esri default basemaps are shared to the custom group.

Clear the web browser’s cache
Clear the browsing history and cache on the machine to ensure a smooth performance of the browser.

The image below shows the basemaps displayed in the Basemap gallery in Portal for ArcGIS Map Viewer.