mongodb/mongoid · error · ArgumentError

No vector search index '#{index}' declared on #{name}

Error message

No vector search index '#{index}' declared on #{name}

What it means

Error "No vector search index '#{index}' declared on #{name}" thrown in mongodb/mongoid.

Source

Thrown at lib/mongoid/search_indexable.rb:435

      def get_indexes(names)
        collection.search_indexes.select { |i| names.include?(i['name']) }
      end

      # Resolves the index name and vector path from the declared specs,
      # applying inference when either is omitted.
      #
      # @param [ String | Symbol | nil ] index The requested index name.
      # @param [ String | Symbol | nil ] path The requested field path.
      #
      # @return [ Array<String> ] the resolved [ index_name, field_path ] pair.
      def resolve_vector_index(index, path)
        vector_specs = search_index_specs.select { |s| s[:type] == 'vectorSearch' }

        raise ArgumentError, "No vector search indexes declared on #{name}" if vector_specs.empty?

        spec = if index
                 found = vector_specs.find { |s| s[:name] == index.to_s }
                 raise ArgumentError, "No vector search index '#{index}' declared on #{name}" unless found

                 found
               elsif vector_specs.size == 1
                 vector_specs.first
               else
                 raise ArgumentError,
                       "#{name} has multiple vector search indexes; specify index: to select one"
               end

        resolved_index = spec[:name] || 'default'
        resolved_path  = path ? path.to_s : infer_vector_path(spec)

        [ resolved_index, resolved_path ]
      end

      # Infers the vector field path from the index definition by locating
      # the first field declared with type 'vector'.
      #

View on GitHub (pinned to 0da0e23d71)

When it happens

Trigger: Thrown at lib/mongoid/search_indexable.rb:435 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/3aea36da82e43939. Report an issue: GitHub.