diff --git a/v3/engine/src/execute/ir/query_root/node_field.rs b/v3/engine/src/execute/ir/query_root/node_field.rs
index ecfb92c0dfc..9e06afa91df 100644
--- a/v3/engine/src/execute/ir/query_root/node_field.rs
+++ b/v3/engine/src/execute/ir/query_root/node_field.rs
@@ -16,6 +16,7 @@ use crate::metadata::resolved;
 use crate::metadata::resolved::subgraph::Qualified;
 use crate::schema::types::{GlobalID, NamespaceAnnotation, NodeFieldTypeNameMapping};
 use crate::schema::GDS;
+use crate::utils::HashMapWithJsonKey;
 
 /// IR for the 'select_one' operation on a model
 #[derive(Serialize, Debug)]
@@ -39,8 +40,10 @@ pub struct NodeSelect<'n, 's> {
 
 fn get_relay_node_namespace_typename_mappings<'s>(
     field_call: &normalized_ast::FieldCall<'s, GDS>,
-) -> Result<&'s HashMap<Qualified<CustomTypeName>, resolved::model::FilterPermission>, error::Error>
-{
+) -> Result<
+    &'s HashMapWithJsonKey<Qualified<CustomTypeName>, resolved::model::FilterPermission>,
+    error::Error,
+> {
     field_call
         .info
         .namespaced
@@ -88,7 +91,7 @@ pub(crate) fn relay_node_ir<'n, 's>(
     let typename_permissions: &'s HashMap<
         Qualified<CustomTypeName>,
         resolved::model::FilterPermission,
-    > = get_relay_node_namespace_typename_mappings(field_call)?;
+    > = &get_relay_node_namespace_typename_mappings(field_call)?.0;
     let typename_mapping = typename_mappings.get(&global_id.typename).ok_or(
         error::InternalDeveloperError::GlobalIDTypenameMappingNotFound {
             type_name: global_id.typename.clone(),
diff --git a/v3/engine/src/schema/query_root/node_field.rs b/v3/engine/src/schema/query_root/node_field.rs
index 18a463503a7..6e2e29ae1e9 100644
--- a/v3/engine/src/schema/query_root/node_field.rs
+++ b/v3/engine/src/schema/query_root/node_field.rs
@@ -17,6 +17,7 @@ use crate::schema::types::{
     Annotation, NodeFieldTypeNameMapping, OutputAnnotation, RootFieldAnnotation,
 };
 use crate::schema::{Role, GDS};
+use crate::utils::HashMapWithJsonKey;
 
 pub(crate) struct RelayNodeFieldOutput {
     pub relay_node_gql_field: gql_schema::Field<GDS>,
@@ -111,7 +112,7 @@ pub(crate) fn relay_node_field(
         relay_node_field_permissions.insert(
             role.clone(),
             Some(types::NamespaceAnnotation::NodeFieldTypeMappings(
-                role_type_permission,
+                HashMapWithJsonKey(role_type_permission),
             )),
         );
     }
diff --git a/v3/engine/src/schema/types.rs b/v3/engine/src/schema/types.rs
index 3728e204c13..82f7629387c 100644
--- a/v3/engine/src/schema/types.rs
+++ b/v3/engine/src/schema/types.rs
@@ -11,9 +11,12 @@ use std::{
 
 use open_dds::{commands, models, types};
 
-use crate::metadata::resolved::{
-    self,
-    subgraph::{Qualified, QualifiedTypeReference},
+use crate::{
+    metadata::resolved::{
+        self,
+        subgraph::{Qualified, QualifiedTypeReference},
+    },
+    utils::HashMapWithJsonKey,
 };
 use strum_macros::Display;
 
@@ -183,7 +186,7 @@ pub enum NamespaceAnnotation {
     /// decoding, a typename will be obtained. We need to use that typename to look up the
     /// Hashmap to get the appropriate `resolved::model::FilterPermission`.
     NodeFieldTypeMappings(
-        HashMap<Qualified<types::CustomTypeName>, resolved::model::FilterPermission>,
+        HashMapWithJsonKey<Qualified<types::CustomTypeName>, resolved::model::FilterPermission>,
     ),
 }
 
diff --git a/v3/engine/src/utils.rs b/v3/engine/src/utils.rs
index 56e7efb6e1e..a84a7f658d5 100644
--- a/v3/engine/src/utils.rs
+++ b/v3/engine/src/utils.rs
@@ -1 +1,92 @@
 pub mod json_ext;
+use serde::{de::DeserializeOwned, ser::SerializeMap, Deserialize, Serialize};
+use std::{collections::HashMap, hash::Hash};
+
+/// HashMapWithJsonKey serializes the key<K> as a String
+/// during serialization and similarly while deserialization, the keys
+/// are expected to be Stringified and it is then deserialized into K.
+/// This type can be helpful when a HashMap<K,V> needs to be serialized,
+/// where K is a custom struct and which serializes into a JSON object
+/// by default, serializing such a HashMap into JSON will throw an error
+/// because JSON spec mandates that the keys in a JSON object be keys.
+/// So, wrapping the HashMap with this type would serialize the Hashmap's
+/// keys as strings and deserialize correspondingly.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct HashMapWithJsonKey<K: Serialize + Eq + Hash + for<'a> Deserialize<'a>, V>(
+    pub HashMap<K, V>,
+);
+
+impl<K: Serialize + for<'a> Deserialize<'a> + Eq + Hash, V: Serialize> Serialize
+    for HashMapWithJsonKey<K, V>
+{
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        let mut map = serializer.serialize_map(Some(self.0.len()))?;
+        for (k, v) in self.0.iter() {
+            let stringified_key = serde_json::to_string(k).map_err(serde::ser::Error::custom)?;
+            map.serialize_entry(&stringified_key, v)?;
+        }
+        map.end()
+    }
+}
+
+impl<'de, K: DeserializeOwned + Hash + Eq + Serialize, V: Deserialize<'de>> Deserialize<'de>
+    for HashMapWithJsonKey<K, V>
+{
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let map: HashMap<String, V> = Deserialize::deserialize(deserializer)?;
+        let mut result = HashMap::new();
+        for (k, v) in map.into_iter() {
+            let k_str = serde_json::from_str(&k).map_err(serde::de::Error::custom)?;
+            result.insert(k_str, v);
+        }
+        Ok(HashMapWithJsonKey(result))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::collections::HashMap;
+
+    use serde::{Deserialize, Serialize};
+
+    use crate::utils::HashMapWithJsonKey;
+
+    #[test]
+    fn test_hashmap_with_serializable_key() {
+        #[derive(Serialize, Deserialize, Hash, PartialEq, Eq, Debug, Clone)]
+        struct Foo {
+            x: u32,
+        }
+
+        let mut test_map: HashMap<Foo, String> = HashMap::new();
+        test_map.insert(Foo { x: 1 }, "hello".to_string());
+
+        // The `test_map` cannot be serialized as is because
+        // the key by default is serialized to a JSON object
+        // and the JSON spec mandates that in a JSON object, the
+        // key must be a String.
+
+        assert!(serde_json::to_string(&test_map).is_err());
+
+        let test_map_with_serializable_key = HashMapWithJsonKey(test_map.clone());
+
+        let serialized_test_map_with_serializable_key =
+            serde_json::to_string(&test_map_with_serializable_key).unwrap();
+
+        assert_eq!(
+            serialized_test_map_with_serializable_key,
+            "{\"{\\\"x\\\":1}\":\"hello\"}"
+        );
+
+        let deserialized_test_map_with_serializable_key: HashMapWithJsonKey<Foo, String> =
+            serde_json::from_str(&serialized_test_map_with_serializable_key).unwrap();
+
+        assert_eq!(test_map, deserialized_test_map_with_serializable_key.0);
+    }
+}
diff --git a/v3/engine/tests/common.rs b/v3/engine/tests/common.rs
index 7ef0f2189a5..8201638ab83 100644
--- a/v3/engine/tests/common.rs
+++ b/v3/engine/tests/common.rs
@@ -65,6 +65,9 @@ pub fn test_execution_expectation_legacy(test_path_string: &str, common_metadata
         let gds = GDS::new(serde_json::from_value(metadata).unwrap()).unwrap();
         let schema = GDS::build_schema(&gds).unwrap();
 
+        // Ensure schema is serialized successfully.
+        serde_json::to_string(&schema).unwrap();
+
         let query = fs::read_to_string(request_path).unwrap();
 
         let session = {
@@ -129,6 +132,9 @@ pub fn test_execution_expectation(test_path_string: &str, common_metadata_paths:
         let gds = GDS::new(serde_json::from_value(metadata).unwrap()).unwrap();
         let schema = GDS::build_schema(&gds).unwrap();
 
+        // Ensure schema is serialized successfully.
+        serde_json::to_string(&schema).unwrap();
+
         let query = fs::read_to_string(request_path).unwrap();
 
         let session_vars_path = &test_path.join("session_variables.json");