diff --git a/lib/errors.js b/lib/errors.js
index e9502e31..eee03326 100644
--- a/lib/errors.js
+++ b/lib/errors.js
@@ -46,7 +46,10 @@ function defaultErrorFormatter (execution, ctx) {
     // it handles fastify errors MER_ERR_GQL_VALIDATION
     if (error.originalError?.errors) {
       // not all errors are `GraphQLError` type, we need to convert them
-      return error.originalError.errors.map(toGraphQLError)
+      if(Array.isArray(error.originalError.errors)){
+        return error.originalError.errors.map(toGraphQLError)
+      }
+      return toGraphQLError(error.originalError.errors)
     }
 
     return error