diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -375,7 +375,8 @@ def concludenode(repo, rev, p1, p2, comm
         targetphase = max(ctx.phase(), phases.draft)
         # retractboundary doesn't overwrite upper phase inherited from parent
         newnode = repo[newrev].node()
-        phases.retractboundary(repo, targetphase, [newnode])
+        if newnode:
+            phases.retractboundary(repo, targetphase, [newnode])
         return newrev
     except util.Abort:
         # Invalidate the previous setparents