diff --git a/Cargo.lock b/Cargo.lock
index d607e35..180493c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -967,7 +967,7 @@ dependencies = [
 
 [[package]]
 name = "ndc-sdk"
-version = "0.2.0"
+version = "0.2.1"
 dependencies = [
  "async-trait",
  "axum",
diff --git a/Cargo.toml b/Cargo.toml
index 00d879f..ed995f2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [workspace]
 resolver = "2"
 
-package.version = "0.2.0"
+package.version = "0.2.1"
 package.edition = "2021"
 package.license = "Apache-2.0"
 
diff --git a/crates/sdk/src/connector/error.rs b/crates/sdk/src/connector/error.rs
index 7d4944d..ccebee0 100644
--- a/crates/sdk/src/connector/error.rs
+++ b/crates/sdk/src/connector/error.rs
@@ -118,11 +118,11 @@ pub enum InitializationError {
 #[derive(Debug, Error)]
 pub enum FetchMetricsError {
     #[error("error fetching metrics: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl FetchMetricsError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     #[must_use]
@@ -154,11 +154,11 @@ impl IntoResponse for FetchMetricsError {
 #[derive(Debug, Error)]
 pub enum HealthError {
     #[error("error checking health status: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl HealthError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     #[must_use]
@@ -190,11 +190,11 @@ impl IntoResponse for HealthError {
 #[derive(Debug, Error)]
 pub enum SchemaError {
     #[error("error retrieving the schema: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl SchemaError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     #[must_use]
@@ -205,8 +205,8 @@ impl SchemaError {
     }
 }
 
-impl From<Box<dyn Error>> for SchemaError {
-    fn from(value: Box<dyn Error>) -> Self {
+impl From<Box<dyn Error + Send + Sync>> for SchemaError {
+    fn from(value: Box<dyn Error + Send + Sync>) -> Self {
         Self::new(value)
     }
 }
@@ -247,11 +247,11 @@ pub enum QueryError {
     #[error("unsupported operation: {}", .0.message)]
     UnsupportedOperation(models::ErrorResponse),
     #[error("error executing query: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl QueryError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     pub fn new_invalid_request<T: ToString>(message: &T) -> Self {
@@ -289,8 +289,8 @@ impl QueryError {
     }
 }
 
-impl From<Box<dyn Error>> for QueryError {
-    fn from(value: Box<dyn Error>) -> Self {
+impl From<Box<dyn Error + Send + Sync>> for QueryError {
+    fn from(value: Box<dyn Error + Send + Sync>) -> Self {
         Self::new(value)
     }
 }
@@ -334,11 +334,11 @@ pub enum ExplainError {
     #[error("unsupported operation: {}", .0.message)]
     UnsupportedOperation(models::ErrorResponse),
     #[error("explain error: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl ExplainError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     pub fn new_invalid_request<T: ToString>(message: &T) -> Self {
@@ -376,8 +376,8 @@ impl ExplainError {
     }
 }
 
-impl From<Box<dyn Error>> for ExplainError {
-    fn from(value: Box<dyn Error>) -> Self {
+impl From<Box<dyn Error + Send + Sync>> for ExplainError {
+    fn from(value: Box<dyn Error + Send + Sync>) -> Self {
         Self::new(value)
     }
 }
@@ -429,11 +429,11 @@ pub enum MutationError {
     #[error("mutation violates constraint: {}", .0.message)]
     ConstraintNotMet(models::ErrorResponse),
     #[error("error executing mutation: {0}")]
-    Other(Box<dyn Error>, serde_json::Value),
+    Other(Box<dyn Error + Send + Sync>, serde_json::Value),
 }
 
 impl MutationError {
-    pub fn new<E: Into<Box<dyn Error>>>(err: E) -> Self {
+    pub fn new<E: Into<Box<dyn Error + Send + Sync>>>(err: E) -> Self {
         Self::Other(err.into(), serde_json::Value::Null)
     }
     pub fn new_invalid_request<T: ToString>(message: &T) -> Self {
@@ -489,8 +489,8 @@ impl MutationError {
     }
 }
 
-impl From<Box<dyn Error>> for MutationError {
-    fn from(value: Box<dyn Error>) -> Self {
+impl From<Box<dyn Error + Send + Sync>> for MutationError {
+    fn from(value: Box<dyn Error + Send + Sync>) -> Self {
         Self::new(value)
     }
 }
diff --git a/crates/sdk/src/default_main.rs b/crates/sdk/src/default_main.rs
index 6c926d3..07b5b26 100644
--- a/crates/sdk/src/default_main.rs
+++ b/crates/sdk/src/default_main.rs
@@ -448,15 +448,15 @@ mod ndc_test_commands {
         ) -> Result<ndc_models::CapabilitiesResponse, ndc_test::error::Error> {
             super::get_capabilities::<C>()
                 .await
-                .into_value::<Box<dyn std::error::Error>>()
-                .map_err(ndc_test::error::Error::OtherError)
+                .into_value::<Box<dyn std::error::Error + Send + Sync>>()
+                .map_err(|e| ndc_test::error::Error::OtherError(e))
         }
 
         async fn get_schema(&self) -> Result<ndc_models::SchemaResponse, ndc_test::error::Error> {
             match C::get_schema(&self.configuration).await {
                 Ok(response) => response
-                    .into_value::<Box<dyn std::error::Error>>()
-                    .map_err(ndc_test::error::Error::OtherError),
+                    .into_value::<Box<dyn std::error::Error + Send + Sync>>()
+                    .map_err(|e| ndc_test::error::Error::OtherError(e)),
                 Err(err) => Err(ndc_test::error::Error::OtherError(err.into())),
             }
         }
diff --git a/crates/sdk/src/json_response.rs b/crates/sdk/src/json_response.rs
index 4789177..85be6e8 100644
--- a/crates/sdk/src/json_response.rs
+++ b/crates/sdk/src/json_response.rs
@@ -27,7 +27,9 @@ impl<A: (for<'de> serde::Deserialize<'de>)> JsonResponse<A> {
     ///
     /// This is only intended for testing and compatibility. If it lives on a
     /// critical path, we recommend you avoid it.
-    pub(crate) fn into_value<E: From<Box<dyn std::error::Error>>>(self) -> Result<A, E> {
+    pub(crate) fn into_value<E: From<Box<dyn std::error::Error + Send + Sync>>>(
+        self,
+    ) -> Result<A, E> {
         match self {
             Self::Value(value) => Ok(value),
             Self::Serialized(bytes) => {