diff --git a/src/api/client_server/errors/api_error.rs b/src/api/client_server/errors/api_error.rs
new file mode 100644
index 0000000..33b9158
--- /dev/null
+++ b/src/api/client_server/errors/api_error.rs
@@ -0,0 +1,53 @@
+use axum::http::StatusCode;
+use axum::response::IntoResponse;
+
+use super::registration_error::RegistrationError;
+
+macro_rules! map_err {
+    ($err:ident, $($type:path => $target:path),+) => {
+        $(
+            if $err.is::<$type>() {
+                return $target($err.downcast().unwrap());
+            }
+        )*
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum ApiError {
+    #[error("Registration Error")]
+    RegistrationError(#[from] RegistrationError),
+
+    #[error("Database Error")]
+    DBError(#[from] sqlx::Error),
+
+    #[error("Generic Error")]
+    Generic(anyhow::Error),
+}
+
+impl From<anyhow::Error> for ApiError {
+    fn from(err: anyhow::Error) -> Self {
+        map_err!(err,
+            sqlx::Error       => ApiError::DBError,
+            RegistrationError => ApiError::RegistrationError
+        );
+
+        ApiError::Generic(err)
+    }
+}
+
+impl IntoResponse for ApiError {
+    fn into_response(self) -> axum::response::Response {
+        match self {
+            ApiError::RegistrationError(registration_error) => match registration_error {
+                RegistrationError::InvalidUserId => {
+                    (StatusCode::OK, String::new()).into_response()
+                }
+                RegistrationError::MissingUserId => {
+                    (StatusCode::OK, String::new()).into_response()
+                }
+            },
+            _ => StatusCode::INTERNAL_SERVER_ERROR.into_response()
+        }
+    }
+}
diff --git a/src/api/client_server/errors/mod.rs b/src/api/client_server/errors/mod.rs
new file mode 100644
index 0000000..5072c0c
--- /dev/null
+++ b/src/api/client_server/errors/mod.rs
@@ -0,0 +1,2 @@
+pub mod api_error;
+pub mod registration_error;
diff --git a/src/api/client_server/errors/registration_error.rs b/src/api/client_server/errors/registration_error.rs
new file mode 100644
index 0000000..5ca506f
--- /dev/null
+++ b/src/api/client_server/errors/registration_error.rs
@@ -0,0 +1,7 @@
+#[derive(Debug, thiserror::Error)]
+pub enum RegistrationError {
+    #[error("UserId is missing")]
+    MissingUserId,
+    #[error("UserId is invalid")]
+    InvalidUserId,
+}