diff --git a/doc/source/reprepro.rst b/doc/source/reprepro.rst
index 2b8d43c8d2..20479a7341 100644
--- a/doc/source/reprepro.rst
+++ b/doc/source/reprepro.rst
@@ -203,6 +203,10 @@ from the checksums database with a command similar to::
 
 They should come back with the next update.
 
+The ``contents.cache.db`` can be regenerated with the ``export``
+command; this is run by the ``reprepro`` driver scripts automatically.
+It will take some time to regenerate, so this should be run manually.
+
 In some situations where things are very out of sync, it may be easier
 to remove and replace an entire section of the repository.  For
 example, if during updates files within ``xenial-security`` are seen