Currently, the MultiCollectionRouter does not include the main namespace (nss) as part of the involved namespaces, preventing the shard version from being attached twice. This decision impacts the retriability of the StaleConfig exception, as the existing code assumes that the router role will not refresh if the namespace that triggered the exception is not included in the involved namespaces.

As a result, the main namespace does not refresh its routing information.

Today this is not an issue because the StaleConfig exception is handled by the shard role, which refreshes the filtering information. Consequently, this leads to an update of the routing information. Since this exception is retriable, the command will be retried and will succeed with the most current routing information.

However, once SERVER-95393 is implemented, the filtering metadata will no longer refresh the routing information, causing a StaleConfig exception to be returned to the user without converging.