Maintain a fiscal year variant for calendar weeks

What causes this issue?

You want to execute manual planning for a planning step in which 'week'
has been defined as the storage periodicity.
However, there is no suitable fiscal year variant for this storage
periodicity.
A storage periodicity is required in planning for the following:
Breaking down formulas with period fields with column definitions that
are applicable for all fiscal years in a planning layout
Applying distribution keys to column definitions that apply to all
fiscal years
Determining the first day in a period for currency conversion

System Response

You cannot enter manual planning for storage periodicity 'week'.

How to fix this error?

Maintain a suitable fiscal year variant or change the storage
periodicity for the relevant planning step in
<DS:SIMG.SIMG_CFMENUORFBOB29>Customizing</>.

Procedure for System Administrators

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

Error message extract from SAP system. Copyright SAP SE.