Special period $ is not valid -> Check entry

What causes this issue?

Special period &V1& is not valid.
IF &V2& = &V3&
No special period was defined for the fiscal year variant.
ELSE
The value must be greater than &V2& (number of posting periods) and
smaller or equal to &V3&. If you require a posting period, you should
not make an entry for the special period.
ENDIF

How to fix this error?

If you do not enter the special period, the system will derive the
posting period from the posting date. Alternatively, you can enter a
valid special period.

Error message extract from SAP system. Copyright SAP SE.