KeyError: 'closing-route-maps' when granting view permission

On our site using Plone 5.0.7 , there's a particular page that, when changing permissions through the @@sharing page, generates the following error. It doesn't seem to matter which user or which permission we try to grant, but the same actions do succeed on other pages in the same site.

Thanks for any insight you might have.

Traceback (innermost last):
  Module ZPublisher.Publish, line 138, in publish
  Module ZPublisher.mapply, line 77, in mapply
  Module ZPublisher.Publish, line 48, in call_object
  Module, line 59, in __call__
  Module, line 109, in handle_form
  Module Products.CMFCore.CMFCatalogAware, line 108, in reindexObjectSecurity
  Module Products.ZCatalog.CatalogBrains, line 80, in _unrestrictedGetObject
  Module OFS.Traversable, line 300, in unrestrictedTraverse
   - __traceback_info__: ([], 'closing-route-maps')
KeyError: 'closing-route-maps'

Looka like a catalog inconsitency.
Reindex portal_catalog first.

Thank you -- this appears to solve the problem, at least in dev. Will reindex production this evening and see.

Yes! This fixed the issue in production as well. Thank you for your help!