Oracle Database Error Code ORA-30452 Description :
cannot compute AVG(X), VARIANCE(X) or STDDEV(X), without COUNT(X) or SUM(X)
Error Cause:
Incremental refresh of summaries requires a COUNT(X) column in order to incrementally refresh AVG(X). It requires both SUM(X) and COUNT(X) columns in order to in refresh STDDEV(X) or VARIANCE(X)

How to Solve :
Make sure that the required columns are part of the summary definition if incremental refresh capability is desired.