diff --git a/src/aggregation/agg_req.rs b/src/aggregation/agg_req.rs
index ca6ff48a9..8e3599108 100644
--- a/src/aggregation/agg_req.rs
+++ b/src/aggregation/agg_req.rs
@@ -44,22 +44,49 @@ use super::metric::{
 /// The key is the user defined name of the aggregation.
 pub type Aggregations = HashMap<String, Aggregation>;
 
-#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
 /// Aggregation request.
 ///
 /// An aggregation is either a bucket or a metric.
+#[derive(Clone, Debug, PartialEq, Serialize, Deserialize)]
+#[serde(try_from = "AggregationForDeserialization")]
 pub struct Aggregation {
     /// The aggregation variant, which can be either a bucket or a metric.
     #[serde(flatten)]
     pub agg: AggregationVariants,
-    /// The sub_aggregations, only valid for bucket type aggregations. Each bucket will aggregate
     /// on the document set in the bucket.
     #[serde(rename = "aggs")]
-    #[serde(default)]
     #[serde(skip_serializing_if = "Aggregations::is_empty")]
     pub sub_aggregation: Aggregations,
 }
 
+/// In order to display proper error message, we cannot rely on flattening
+/// the json enum. Instead we introduce an intermediary struct to separate
+/// the aggregation from the subaggregation.
+#[derive(Deserialize)]
+struct AggregationForDeserialization {
+    #[serde(flatten)]
+    pub aggs_remaining_json: serde_json::Value,
+    #[serde(rename = "aggs")]
+    #[serde(default)]
+    pub sub_aggregation: Aggregations,
+}
+
+impl TryFrom<AggregationForDeserialization> for Aggregation {
+    type Error = serde_json::Error;
+
+    fn try_from(value: AggregationForDeserialization) -> serde_json::Result<Self> {
+        let AggregationForDeserialization {
+            aggs_remaining_json,
+            sub_aggregation,
+        } = value;
+        let agg: AggregationVariants = serde_json::from_value(aggs_remaining_json)?;
+        Ok(Aggregation {
+            agg,
+            sub_aggregation,
+        })
+    }
+}
+
 impl Aggregation {
     pub(crate) fn sub_aggregation(&self) -> &Aggregations {
         &self.sub_aggregation
diff --git a/src/aggregation/agg_tests.rs b/src/aggregation/agg_tests.rs
index 66aff3a4c..ce7a21212 100644
--- a/src/aggregation/agg_tests.rs
+++ b/src/aggregation/agg_tests.rs
@@ -558,10 +558,10 @@ fn test_aggregation_invalid_requests() -> crate::Result<()> {
 
     assert_eq!(agg_req_1.is_err(), true);
     // TODO: This should list valid values
-    assert_eq!(
-        agg_req_1.unwrap_err().to_string(),
-        "no variant of enum AggregationVariants found in flattened data"
-    );
+    assert!(agg_req_1
+        .unwrap_err()
+        .to_string()
+        .contains("unknown variant `doesnotmatchanyagg`, expected one of"));
 
     // TODO: This should return an error
     // let agg_res = avg_on_field("not_exist_field").unwrap_err();
diff --git a/src/query/boost_query.rs b/src/query/boost_query.rs
index 1b6be6031..85397243a 100644
--- a/src/query/boost_query.rs
+++ b/src/query/boost_query.rs
@@ -2,7 +2,6 @@ use std::fmt;
 
 use crate::docset::BUFFER_LEN;
 use crate::fastfield::AliveBitSet;
-use crate::query::explanation::does_not_match;
 use crate::query::{EnableScoring, Explanation, Query, Scorer, Weight};
 use crate::{DocId, DocSet, Score, SegmentReader, Term};