diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -2267,10 +2267,12 @@
                     self._write_docket(transaction)
             finally:
                 self._writinghandles = None
+                if dfh is not None:
+                    dfh.close()
+                # closing the index file last to avoid exposing referent to
+                # potential unflushed data content.
                 if ifh is not None:
                     ifh.close()
-                if dfh is not None:
-                    dfh.close()
 
     def _write_docket(self, transaction):
         """write the current docket on disk