MONGOID: #{model} has shard config but is not persisted in a

Error message

MONGOID: #{model} has shard config but is not persisted in a sharded cluster: #{model.collection.cluster.summary}

What it means

Error "MONGOID: #{model} has shard config but is not persisted in a sharded cluster: #{model.collection.cluster.summary}" thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/tasks/database.rb:184

      # Returns the model classes that have had their collections sharded,
      # including model classes whose collections had already been sharded
      # prior to the invocation of this method.
      #
      # @example Shard all collections
      #   Mongoid::Tasks::Database.shard_collections
      #
      # @return [ Array<Class> ] The sharded models
      def shard_collections(models = ::Mongoid.models)
        models.map do |model|
          next if model.shard_config.nil?

          if model.embedded? && !model.cyclic?
            logger.warn("MONGOID: #{model} has shard config but is embedded")
            next
          end

          unless model.collection.cluster.sharded? || model.collection.cluster.load_balanced?
            logger.warn("MONGOID: #{model} has shard config but is not persisted in a sharded cluster: #{model.collection.cluster.summary}")
            next
          end

          # Database of the collection must exist in order to run collStats.
          # Depending on server version, the collection itself must also
          # exist.
          # MongoDB does not have a command to create the database; the best
          # approximation of it is to create the collection we want.
          # On older servers, creating a collection that already exists is
          # an error.
          # Additionally, 3.6 and potentially older servers do not provide
          # the error code when they are asked to collStats a non-existent
          # collection (https://jira.mongodb.org/browse/SERVER-50070).
          begin
            model.collection.database.command(collStats: model.collection.name).first
          rescue Mongo::Error::OperationFailure => e
            # Code 26 is database does not exist.
            # Code 8 is collection does not exist, as of 4.0.

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/tasks/database.rb:184 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of mongodb/mongoid@0da0e23d71 (2026-08-23). Data as JSON: /api/errors/bd41360813ff356e. Report an issue: GitHub.