Currently, any failed request to the source Wiki will result in the target Wikibase entering an error state. This behavior is the case even in non-critical situations such as displaying property labels on the revision history page for an item. Please note when discussing this story that a similar issue exists on the Special:RecentChanges page and diff pages when the federation source wiki is unavailable.
If displaying federated properties is not possible when loading an edit summary due to a failed call to the source Wiki, then we should format the edit summaries differently, displaying only PIDs rather than displaying an error page.
Given My connection to the source Wiki is unavailable
When I load a revision history page or recent changes page that involves statements with federated properties
Then the page loads without labels for the properties, just linked PIDs.
Note: This should be testable using ModHeader in the test system.