diff --git a/spacy/pipeline/coref.py b/spacy/pipeline/coref.py
index 7cf4fa44a..b58441bf9 100644
--- a/spacy/pipeline/coref.py
+++ b/spacy/pipeline/coref.py
@@ -289,7 +289,7 @@ class CoreferenceResolver(TrainablePipe):
                 span = example.predicted.char_span(start_char, end_char)
                 if span is None:
                     # TODO log more details
-                    raise IndexError(Errors.E1043)
+                    raise IndexError(Errors.E1044)
                 cc.append((span.start, span.end))
             clusters.append(cc)