A method might not be attached to any generic function. In that case print it as UNNAMED.

src/CHANGELOG

@@ -32,6 +32,9 @@ ECL 0.9h
    a syntax error to have a denominator full of zeros (CLHS 2.2 end plus
    2.3.2.1.2).
 
+ - When a DEFMETHOD form had an incongruent lambda list, an internal error
+   prevented ECL from writing the proper error message.
+
 * Design:
 
  - Simplified the structure of the frame stack, removing redundant fields.

src/clos/print.lsp

@@ -103,7 +103,11 @@
 
 (defmethod print-object ((m standard-method) stream)
   (print-unreadable-object (m stream :type t)
-    (format stream "~A ~A" (generic-function-name (method-generic-function m))
+    (format stream "~A ~A"
+	    (let ((gf (method-generic-function m)))
+	      (if gf
+		  (generic-function-name gf)
+		  'UNNAMED))
 	    (method-specializers m)))
   m)