Problem: Unable to load the ArcGIS Online basemap gallery
When clicking the Basemap button in the ArcGIS Online map viewer, the full Esri basemap gallery fails to display.
Possible causes for this issue are:
The configured security settings allows for mixed content of HTTP and HTTPS. The common error displays when faced with this issue is "403 Forbidden error". This is a HTTP status code which indicates access to the particular web page is denied.
The following ArcGIS Online Help document describes the behavior of using mixed content environment: ArcGIS Online Help: Troubleshoot.
The ArcGIS Online basemap gallery display does not load after a recent ArcGIS Online update.
Solution or Workaround
The following are possible solutions for this issue:
Use the ArcGIS Online Health Dashboard The ArcGIS Online Health Dashboard is a status page, which provides current information regarding the service availability of ArcGIS Online. The information provided here is for the overall health of the ArcGIS Online system. A Service disruption message is returned when a particular service becomes unavailable. The ArcGIS Online Health Dashboard page can be viewed at: ArcGIS Online Health Dashboard.
Configure ArcGIS Online with the appropriate security settings Certain layers do not display properly with mixed content. This also depends on the web browser used to view the content. The following ArcGIS Online help document describes the security options available and how to configure the security settings: Configure Security settings.
Re-associate the default Esri basemaps with the basemap gallery
The following steps detail this workflow:
Log in to ArcGIS Online with an administrator account.
Click My Organization > Edit Settings > Map.
Take note of the group selected under Basemap Gallery.
Create a new Group to store the default Esri basemaps.
Click Groups > CREATE A GROUP.
Give the newly created group a name and leave all other options to default.
Change the Group used for the Basemap Gallery.
Click My Organization > click EDIT SETTINGS > click Map.
From the Basemap Gallery option, click the drop-down arrow, and select the newly created group.
Check the Share the Esri default basemaps to this group when you click Save option. Checking this option includes the default Esri basemaps within the newly created group.
Click Map, and click the Basemap widget to verify if the basemap gallery is available.