Hive Terminal RuntimeException after query execution - sql

Question

I have executed this query on HIVE, using that dataset:
https://data.europa.eu/data/datasets/erasmus-mobility-statistics-2014-2019-v2?locale=en:
select i.foe, i.pn, i.massimo
from
(
SELECT m.foe, m.pn, max(m.somma) AS massimo
FROM
(
select pn, foe, sum(participants) as somma
from erasmus
WHERE foe <> "? Unknown ?" and participants>0
group by foe, pn
) as m
group by m.foe, m.pn
) as i
where i.massimo=
(
select sum(participants) as somma
from erasmus
WHERE foe <> "? Unknown ?" and participants>0 AND i.foe=foe
group by foe, pn
)
At the end of execution I get this error back:
Error: java.lang.RuntimeException: org.apache.hadoop.hive.ql.metadata.HiveException: Hive Runtime Error while processing row (tag=0) {"key":{"_col0":"Audio-visual techniques and media production","_col1":"AD"},"value":null}
caused by: org.apache.hadoop.hive.ql.exec.UDFArgumentException: Scalar subquery expression returns more than one row.
How can I solve this? Thank you.