diff --git a/crates/common/src/errors.rs b/crates/common/src/errors.rs
new file mode 100644
index 00000000..fd634915
--- /dev/null
+++ b/crates/common/src/errors.rs
@@ -0,0 +1,39 @@
+use proxy_wasm::types::Status;
+
+use crate::ratelimit;
+
+#[derive(thiserror::Error, Debug)]
+pub enum ClientError {
+    #[error("Error dispatching HTTP call to `{upstream_name}/{path}`, error: {internal_status:?}")]
+    DispatchError {
+        upstream_name: String,
+        path: String,
+        internal_status: Status,
+    },
+}
+
+#[derive(thiserror::Error, Debug)]
+pub enum ServerError {
+    #[error(transparent)]
+    HttpDispatch(ClientError),
+    #[error(transparent)]
+    Deserialization(serde_json::Error),
+    #[error(transparent)]
+    Serialization(serde_json::Error),
+    #[error("{0}")]
+    LogicError(String),
+    #[error("upstream error response authority={authority}, path={path}, status={status}")]
+    Upstream {
+        authority: String,
+        path: String,
+        status: String,
+    },
+    #[error("jailbreak detected: {0}")]
+    Jailbreak(String),
+    #[error("{why}")]
+    NoMessagesFound { why: String },
+    #[error(transparent)]
+    ExceededRatelimit(ratelimit::Error),
+    #[error("{why}")]
+    BadRequest { why: String },
+}