diff --git a/quiche/quic/core/quic_error_codes.cc b/quiche/quic/core/quic_error_codes.cc
index c0ea59d..e63141b 100644
--- a/quiche/quic/core/quic_error_codes.cc
+++ b/quiche/quic/core/quic_error_codes.cc
@@ -281,6 +281,7 @@
     RETURN_STRING_LITERAL(QUIC_TLS_KEYING_MATERIAL_EXPORTS_MISMATCH);
     RETURN_STRING_LITERAL(QUIC_TLS_KEYING_MATERIAL_EXPORT_NOT_AVAILABLE);
     RETURN_STRING_LITERAL(QUIC_UNEXPECTED_DATA_BEFORE_ENCRYPTION_ESTABLISHED);
+    RETURN_STRING_LITERAL(QUIC_SERVER_UNHEALTHY);
 
     RETURN_STRING_LITERAL(QUIC_LAST_ERROR);
     // Intentionally have no default case, so we'll break the build
@@ -790,6 +791,8 @@
       return {true, static_cast<uint64_t>(PROTOCOL_VIOLATION)};
     case QUIC_UNEXPECTED_DATA_BEFORE_ENCRYPTION_ESTABLISHED:
       return {true, static_cast<uint64_t>(PROTOCOL_VIOLATION)};
+    case QUIC_SERVER_UNHEALTHY:
+      return {true, static_cast<uint64_t>(INTERNAL_ERROR)};
     case QUIC_LAST_ERROR:
       return {false, static_cast<uint64_t>(QUIC_LAST_ERROR)};
   }
diff --git a/quiche/quic/core/quic_error_codes.h b/quiche/quic/core/quic_error_codes.h
index 9c20cd5..34fc0c1 100644
--- a/quiche/quic/core/quic_error_codes.h
+++ b/quiche/quic/core/quic_error_codes.h
@@ -614,8 +614,11 @@
   QUIC_TLS_KEYING_MATERIAL_EXPORT_NOT_AVAILABLE = 210,
   QUIC_UNEXPECTED_DATA_BEFORE_ENCRYPTION_ESTABLISHED = 211,
 
+  // Error code related to backend health-check.
+  QUIC_SERVER_UNHEALTHY = 213,
+
   // No error. Used as bound while iterating.
-  QUIC_LAST_ERROR = 213,
+  QUIC_LAST_ERROR = 214,
 };
 // QuicErrorCodes is encoded as four octets on-the-wire when doing Google QUIC,
 // or a varint62 when doing IETF QUIC. Ensure that its value does not exceed