diff --git a/hgext3rd/clindex.pyx b/hgext3rd/clindex.pyx
--- a/hgext3rd/clindex.pyx
+++ b/hgext3rd/clindex.pyx
@@ -370,6 +370,7 @@
 # Simple utilities to log debug messages
 def _logandraise(vfs, message):
     _log(vfs, message)
+    _recover(vfs)
     raise RuntimeError(message)
 
 def _logifraise(vfs, func, infofunc):
@@ -377,8 +378,13 @@
         return func()
     except RuntimeError as ex:
         _log(vfs, 'exception: %r %r' % (ex, infofunc()))
+        _recover(vfs)
         raise
 
+def _recover(vfs):
+    vfs.tryunlink('nodemap')
+    vfs.tryunlink('childmap')
+
 _logpath = None
 
 def _log(vfs, message):