What causes this issue?

The report/variant definition determined that the characteristic &V1&
(with the field name &V2&)should be used for summarizing.

System Response

The data is summarized using characteristic &V1&.
Characteristic &V1& was initialized
Under the assumption that all key figures relevant for the
characteristic &V1& are additive, meaning that they accumulate when
summarized using &V1&

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

More complex forms of aggregating the data such as you can set for key
figures (for example, MAX, MIN, AVG etc) are not taken into account when
summarizing.

How to fix this error?

If any irregularities occur, check if one of the points above applies.
If not, adjust the report/variant definition so that summarization is
done using only those characteristics for which the key figuresare
additive.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.