The Add Basemap, Add Data From ArcGIS Online, and Add Data From Portal for ArcGIS options are disabled in ArcMap. In some instances, the Add Basemap window opens, but disappears before a basemap is added to the data frame.
This issue can be caused by a number of reasons. Refer to the following Support Services Blog post, Troubleshooting issues adding ArcGIS Online basemaps to ArcMap to identify the cause of the issue. If none of the causes are applicable, the issue is likely caused if a system file is corrupted or if the ArcGIS Online globe icon in the system tray is disconnected.
Rename the Esri folders from the Roaming folder and the Registry Editor window.
Note: Ensure the connection with ArcGIS Online is established by hovering over the globe icon in the system tray. If the globe icon shows as disconnected, right-click the icon > Properties > Enable ArcGIS Connection.
Use the following steps only when the Add Basemap and Add Data from ArcGIS Online button are still grayed out, despite the connection being established.
Warning: The instructions below include making changes to essential parts of your operating system. It is recommended to back up your operating system and files, including the registry, before proceeding. Consult a qualified computer systems professional, if necessary. Renaming the ESRI folders is a factory reset of ArcGIS, and therefore all third-party tools, custom scripts, and custom toolbars currently installed must be reinstalled as a result. Additionally, all existing folder connections must be reconnected. Esri cannot guarantee results from incorrect modifications while following these instructions. Use caution and proceed at your own risk.
Rename the ESRI folder in the Roaming folder
The location of the User Profile depends on the operating system.
C:\Documents and Settings\<UserProfile>\Application Data\ESRI\
Note: The Application Data (or AppData) folder is hidden by default. If unable to locate the folder, enable 'Show Hidden Files and Folders' via Folder Options. Alternatively, type '%APPDATA%' in the Windows Explorer address bar. This directs to the folder containing the ESRI folder, regardless of the Windows version and the 'hidden' settings.
Rename the ESRI folder in the Registry Editor window