InfoCube &1 is not a real-time InfoCube

What causes this issue?

In the context of the planning area you have executed an action for
which you need to know the technical attributes of the InfoCube on which
it is based, before you continue working:
You can assign InfoCubes, RemoteProviders and MultiProviders to a
planning area.
However, you can only have read access to MultiProviders,
RemoteProviders and standard InfoCubes.
Plan data can only be written in real-time InfoCubes. The InfoCube that
is linked to the current planning area is not a real-time InfoCube.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Decide which tasks you want to execute in the current planning area:
If you only want to display data in the current planning area, then
continue processing the planning area.
If you want to change data or enter new data, then proceed in one of the
following ways:
Assign a real-time InfoCube to the planning area.
If the InfoCube is not a real-time InfoCube, convert the InfoCube to
real time in the Data Warehousing Workbench in the SAP Business
Information Warehouse.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.