diff --git a/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/Utils/rpc_client.rb b/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/Utils/rpc_client.rb
index be755d5a0..963ed336f 100644
--- a/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/Utils/rpc_client.rb
+++ b/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/Utils/rpc_client.rb
@@ -32,16 +32,26 @@ def initialize(api_url, auth_secret)
 
       # rubocop:disable Metrics/ParameterLists
       def call_rpc(endpoint, caller: nil, method: :get, payload: nil, symbolize_keys: false, if_none_match: nil)
+        resp = call_rpc_raw(endpoint, caller: caller, method: method, payload: payload,
+                                      symbolize_keys: symbolize_keys, if_none_match: if_none_match)
+        return resp if resp == NotModified
+
+        resp.body
+      end
+
+      def call_rpc_raw(endpoint, caller: nil, method: :get, payload: nil, symbolize_keys: false, if_none_match: nil)
         response = make_request(endpoint, caller: caller, method: method, payload: payload,
                                           symbolize_keys: symbolize_keys, if_none_match: if_none_match)
-        handle_response(response)
-      end
+        return NotModified if response.status == HTTP_NOT_MODIFIED
+
+        raise_appropriate_error(response) unless response.success?
 
+        response
+      end
       # rubocop:enable Metrics/ParameterLists
 
       def fetch_schema(endpoint, if_none_match: nil)
-        response = make_request(endpoint, method: :get, symbolize_keys: true, if_none_match: if_none_match)
-        handle_response(response)
+        call_rpc(endpoint, method: :get, symbolize_keys: true, if_none_match: if_none_match)
       end
 
       private
@@ -111,13 +121,6 @@ def generate_signature(timestamp)
         OpenSSL::HMAC.hexdigest('SHA256', @auth_secret, timestamp)
       end
 
-      def handle_response(response)
-        return response.body if response.success?
-        return NotModified if response.status == HTTP_NOT_MODIFIED
-
-        raise_appropriate_error(response)
-      end
-
       def raise_appropriate_error(response)
         error_body = parse_error_body(response)
         status = response.status
diff --git a/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/collection.rb b/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/collection.rb
index 46a17c196..acf0bbb86 100644
--- a/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/collection.rb
+++ b/packages/forest_admin_datasource_rpc/lib/forest_admin_datasource_rpc/collection.rb
@@ -1,4 +1,7 @@
 require 'base64'
+require 'cgi'
+require 'json'
+require 'stringio'
 
 module ForestAdminDatasourceRpc
   class Collection < ForestAdminDatasourceToolkit::Collection
@@ -127,7 +130,12 @@ def execute(caller, name, data, filter = nil)
         "Forwarding '#{@name}' action #{name} call to the Rpc agent on #{url}."
       )
 
-      @client.call_rpc(url, caller: caller, method: :post, payload: params, symbolize_keys: true)
+      response = @client.call_rpc_raw(url, caller: caller, method: :post, payload: params,
+                                           symbolize_keys: true)
+
+      return build_file_result(response) if response.headers['x-forest-action-type'] == 'File'
+
+      response.body
     end
 
     def get_form(caller, name, data = nil, filter = nil, metas = nil)
@@ -176,5 +184,20 @@ def encode_form_data(data)
         end
       end
     end
+
+    def build_file_result(response)
+      response_headers_header = response.headers['x-forest-action-response-headers']
+      file_name_header = response.headers['x-forest-action-file-name']
+
+      result = {
+        type: 'File',
+        mime_type: response.headers['content-type'],
+        name: CGI.unescape(file_name_header.to_s),
+        stream: response.body.to_s
+      }
+      result[:response_headers] = JSON.parse(response_headers_header) if response_headers_header
+
+      result
+    end
   end
 end
diff --git a/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/collection_spec.rb b/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/collection_spec.rb
index 0d307ec67..fff27c825 100644
--- a/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/collection_spec.rb
+++ b/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/collection_spec.rb
@@ -7,17 +7,20 @@ module ForestAdminDatasourceRpc
   include ForestAdminDatasourceToolkit::Components::Query::ConditionTree
 
   describe Collection do
+    let(:raw_response) do
+      instance_double(Faraday::Response, body: {}, headers: {}, status: 200, success?: true)
+    end
+    let(:rpc_client) { instance_double(Utils::RpcClient, call_rpc: {}, call_rpc_raw: raw_response) }
+    let(:datasource) { Datasource.new({ uri: 'http://localhost' }, introspection) }
+    let(:collection) { datasource.get_collection('Product') }
+    let(:caller) { build_caller }
+
     before do
       logger = instance_double(Logger, log: nil)
       allow(ForestAdminAgent::Facades::Container).to receive_messages(logger: logger, cache: 'secret')
       allow(Utils::RpcClient).to receive(:new).and_return(rpc_client)
     end
 
-    let(:rpc_client) { instance_double(Utils::RpcClient, call_rpc: {}) }
-    let(:datasource) { Datasource.new({ uri: 'http://localhost' }, introspection) }
-    let(:collection) { datasource.get_collection('Product') }
-    let(:caller) { build_caller }
-
     include_context 'with introspection'
 
     context 'when initialized' do
@@ -251,7 +254,7 @@ module ForestAdminDatasourceRpc
 
         collection.execute(caller, 'my_action', data)
 
-        expect(rpc_client).to have_received(:call_rpc) do |url, options|
+        expect(rpc_client).to have_received(:call_rpc_raw) do |url, options|
           expect(url).to eq('/forest/rpc/Product/action-execute')
           expect(options[:caller]).to eq(caller)
           expect(options[:method]).to eq(:post)
@@ -270,15 +273,15 @@ module ForestAdminDatasourceRpc
         end
       end
 
-      it 'asks the RPC client to symbolize response keys so ActionResult.parse sees :type' do
+      it 'calls call_rpc_raw with symbolized keys so the response headers stay reachable' do
         collection.execute(caller, 'my_action', {})
 
-        expect(rpc_client).to have_received(:call_rpc) do |_url, options|
+        expect(rpc_client).to have_received(:call_rpc_raw) do |_url, options|
           expect(options[:symbolize_keys]).to be(true)
         end
       end
 
-      it 'returns the action result as-is so :type and other keys reach ActionResult.parse' do
+      it 'returns the parsed body so :type and other keys reach ActionResult.parse' do
         success_result = {
           type: 'Success',
           message: 'ok',
@@ -286,13 +289,65 @@ module ForestAdminDatasourceRpc
           html: nil,
           response_headers: {}
         }
-        allow(rpc_client).to receive(:call_rpc).and_return(success_result)
+        allow(raw_response).to receive(:body).and_return(success_result)
 
         result = collection.execute(caller, 'my_action', {})
 
         expect(result).to eq(success_result)
         expect(result[:type]).to eq('Success')
       end
+
+      context 'when the server replies with X-Forest-Action-Type=File' do
+        let(:file_body) { 'binary-payload' }
+        let(:raw_response) do
+          instance_double(
+            Faraday::Response,
+            body: file_body,
+            headers: {
+              'content-type' => 'application/pdf',
+              'x-forest-action-type' => 'File',
+              'x-forest-action-file-name' => CGI.escape('report final.pdf'),
+              'x-forest-action-response-headers' => { 'set-cookie' => 'token=xyz' }.to_json
+            },
+            status: 200,
+            success?: true
+          )
+        end
+
+        it 'rebuilds a File action result from the response headers and body' do
+          result = collection.execute(caller, 'download', {})
+
+          expect(result[:type]).to eq('File')
+          expect(result[:mime_type]).to eq('application/pdf')
+          expect(result[:name]).to eq('report final.pdf')
+          expect(result[:response_headers]).to eq({ 'set-cookie' => 'token=xyz' })
+          expect(result[:stream]).to eq(file_body)
+        end
+
+        context 'when response_headers header is absent' do
+          let(:raw_response) do
+            instance_double(
+              Faraday::Response,
+              body: 'hi',
+              headers: {
+                'content-type' => 'text/plain',
+                'x-forest-action-type' => 'File',
+                'x-forest-action-file-name' => 'note.txt'
+              },
+              status: 200,
+              success?: true
+            )
+          end
+
+          it 'omits response_headers from the rebuilt result' do
+            result = collection.execute(caller, 'download', {})
+
+            expect(result[:type]).to eq('File')
+            expect(result[:name]).to eq('note.txt')
+            expect(result).not_to have_key(:response_headers)
+          end
+        end
+      end
     end
 
     context 'when call get_form' do
diff --git a/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/utils/rpc_client_spec.rb b/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/utils/rpc_client_spec.rb
index 5ff24a78d..1cf32e4b6 100644
--- a/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/utils/rpc_client_spec.rb
+++ b/packages/forest_admin_datasource_rpc/spec/lib/forest_admin_datasource_rpc/utils/rpc_client_spec.rb
@@ -99,6 +99,28 @@ module Utils
         end
       end
 
+      describe '#call_rpc_raw' do
+        let(:response_headers) { { 'x-forest-action-type' => 'File' } }
+        let(:response) do
+          instance_double(Faraday::Response, status: 200, body: {}, success?: true, headers: response_headers)
+        end
+        let(:faraday_connection) { instance_double(Faraday::Connection, send: response) }
+        let(:timestamp) { '2025-04-01T14:07:02Z' }
+
+        before do
+          allow(Faraday::Connection).to receive(:new).and_return(faraday_connection)
+          allow(Time).to receive(:now).and_return(instance_double(Time, utc: instance_double(Time, iso8601: timestamp)))
+        end
+
+        it 'returns the Faraday::Response object so callers can read headers' do
+          result = rpc_client.call_rpc_raw('/rpc/test', method: :post)
+
+          expect(result).to be(response)
+          expect(result.body).to eq({})
+          expect(result.headers).to eq(response_headers)
+        end
+      end
+
       describe '#fetch_schema' do
         let(:response_headers) { {} }
         let(:response) { instance_double(Faraday::Response, status: 200, body: { collections: [] }, success?: true, headers: response_headers) }
diff --git a/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/action_execute.rb b/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/action_execute.rb
index 30d9235e1..6c4fd7b7f 100644
--- a/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/action_execute.rb
+++ b/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/action_execute.rb
@@ -1,3 +1,5 @@
+require 'cgi'
+require 'json'
 require 'jsonapi-serializers'
 
 module ForestAdminRpcAgent
@@ -18,7 +20,31 @@ def handle_request(args)
         data = args[:params]['data']
         action = args[:params]['action']
 
-        collection.execute(args[:caller], action, data, filter)
+        result = collection.execute(args[:caller], action, data, filter)
+
+        return build_file_response(result) if file_result?(result)
+
+        result
+      end
+
+      private
+
+      def file_result?(result)
+        result.is_a?(Hash) && result[:type] == 'File'
+      end
+
+      def build_file_response(result)
+        encoded_name = CGI.escape(result[:name].to_s)
+        headers = {
+          'Content-Type' => result[:mime_type],
+          'Content-Disposition' => %(attachment; filename="#{encoded_name}"),
+          'X-Forest-Action-Type' => 'File',
+          'X-Forest-Action-File-Name' => encoded_name
+        }
+        headers['X-Forest-Action-Response-Headers'] = result[:response_headers].to_json if result[:response_headers]
+
+        # raw: true skips JSON encoding — file streams are arbitrary binary bytes.
+        { status: 200, headers: headers, content: result[:stream], raw: true }
       end
     end
   end
diff --git a/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/base_route.rb b/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/base_route.rb
index c0ab2c20a..01da82071 100644
--- a/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/base_route.rb
+++ b/packages/forest_admin_rpc_agent/lib/forest_admin_rpc_agent/routes/base_route.rb
@@ -26,7 +26,13 @@ def register_sinatra(app)
             status result[:status]
             # Set custom headers if provided
             result[:headers]&.each { |key, value| headers[key] = value }
-            result[:content] ? serialize_response(result[:content]) : ''
+            if result[:content].nil?
+              ''
+            elsif result[:raw]
+              result[:content].to_s
+            else
+              serialize_response(result[:content])
+            end
           else
             serialize_response(result)
           end
@@ -68,7 +74,13 @@ def build_rails_response(result)
         if result.is_a?(Hash) && result.key?(:status)
           response_headers = { 'Content-Type' => 'application/json' }
           response_headers.merge!(result[:headers]) if result[:headers]
-          body = result[:content] ? serialize_response(result[:content]) : ''
+          body = if result[:content].nil?
+                   ''
+                 elsif result[:raw]
+                   result[:content].to_s
+                 else
+                   serialize_response(result[:content])
+                 end
           [result[:status], response_headers, [body]]
         else
           [200, { 'Content-Type' => 'application/json' }, [serialize_response(result)]]
diff --git a/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/action_execute_spec.rb b/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/action_execute_spec.rb
index 16d87e941..4f0305540 100644
--- a/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/action_execute_spec.rb
+++ b/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/action_execute_spec.rb
@@ -94,6 +94,54 @@ module Routes
               .to raise_error(ForestAdminAgent::Http::Exceptions::NotFoundError)
           end
         end
+
+        context 'when the action returns a File result' do
+          let(:binary_payload) { String.new("%PDF-1.4\n%\xE2\xE3\xCF\xD3\n", encoding: 'ASCII-8BIT') }
+          let(:file_result) do
+            {
+              type: 'File',
+              name: 'report final.pdf',
+              mime_type: 'application/pdf',
+              stream: binary_payload,
+              response_headers: { 'set-cookie' => 'token=xyz' }
+            }
+          end
+
+          before do
+            allow(@datasource.get_collection('users'))
+              .to receive(:execute).and_return(file_result)
+          end
+
+          it 'returns a raw HTTP response so the binary content is not JSON-encoded' do
+            response = route.handle_request(args)
+
+            expect(response).to include(status: 200, raw: true)
+            expect(response[:content]).to eq(binary_payload)
+            expect(response[:content].encoding.name).to eq('ASCII-8BIT')
+          end
+
+          it 'sets File-specific headers including the encoded filename' do
+            response = route.handle_request(args)
+            headers = response[:headers]
+
+            expect(headers['Content-Type']).to eq('application/pdf')
+            expect(headers['X-Forest-Action-Type']).to eq('File')
+            expect(headers['X-Forest-Action-File-Name']).to eq(CGI.escape('report final.pdf'))
+            expect(headers['Content-Disposition']).to include(CGI.escape('report final.pdf'))
+            expect(headers['X-Forest-Action-Response-Headers']).to eq({ 'set-cookie' => 'token=xyz' }.to_json)
+          end
+
+          context 'when the action does not provide response_headers' do
+            let(:file_result) do
+              { type: 'File', name: 'note.txt', mime_type: 'text/plain', stream: 'hi' }
+            end
+
+            it 'omits the X-Forest-Action-Response-Headers header' do
+              response = route.handle_request(args)
+              expect(response[:headers]).not_to have_key('X-Forest-Action-Response-Headers')
+            end
+          end
+        end
       end
     end
   end
diff --git a/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/base_route_spec.rb b/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/base_route_spec.rb
index 01a2f4cc4..c4e8bca3d 100644
--- a/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/base_route_spec.rb
+++ b/packages/forest_admin_rpc_agent/spec/lib/forest_admin_rpc_agent/routes/base_route_spec.rb
@@ -19,6 +19,20 @@ def handle_request(_params)
       end
     end
 
+    # Test route that returns a binary payload — emulates an action File result.
+    # The "%\xE2\xE3\xCF\xD3" prefix forces non-UTF8 bytes (the PDF binary marker),
+    # which is exactly what used to crash serialize_response.
+    class BinaryTestRoute < BaseRoute
+      def handle_request(_args)
+        {
+          status: 200,
+          headers: { 'Content-Type' => 'application/pdf' },
+          content: String.new("%PDF-1.4\n%\xE2\xE3\xCF\xD3\nbinary-body-bytes", encoding: 'ASCII-8BIT'),
+          raw: true
+        }
+      end
+    end
+
     describe BaseRoute do
       subject(:route) { TestRoute.new('/test', 'get', 'test_route') }
 
@@ -136,6 +150,43 @@ def handle_request(_params)
             )
           end
         end
+
+        # Integration: exercises the handler proc that register_rails passes
+        # to router.match. This is the only place where binary action results
+        # actually hit Rack — unit tests that stub collection.execute return a
+        # Ruby Hash that never goes through serialize_response.
+        context 'when the handler returns a raw binary response (File action)' do
+          subject(:binary_route) { BinaryTestRoute.new('/binary', 'post', 'binary_test') }
+          let(:expected_bytes) do
+            String.new("%PDF-1.4\n%\xE2\xE3\xCF\xD3\nbinary-body-bytes", encoding: 'ASCII-8BIT')
+          end
+          let(:request) do
+            instance_double(
+              ActionDispatch::Request,
+              path_parameters: {}, query_parameters: {}, request_parameters: {}, env: {}
+            )
+          end
+
+          it 'passes the binary body to Rack untouched (no JSON encoding)' do
+            captured_handler = nil
+            allow(rails_router).to receive(:match) { |_, opts| captured_handler = opts[:to] }
+            binary_route.send(:register_rails, rails_router)
+
+            env = {
+              'REQUEST_METHOD' => 'POST',
+              'PATH_INFO' => '/binary',
+              'QUERY_STRING' => '',
+              'rack.input' => StringIO.new
+            }
+            status, response_headers, body = captured_handler.call(env)
+
+            expect(status).to eq(200)
+            expect(response_headers['Content-Type']).to eq('application/pdf')
+            expect(body).to be_an(Array)
+            expect(body.first).to eq(expected_bytes)
+            expect(body.first.encoding.name).to eq('ASCII-8BIT')
+          end
+        end
       end
 
       describe '#build_rails_response' do
@@ -166,6 +217,23 @@ def handle_request(_params)
             expect(response[1]).to eq({ 'Content-Type' => 'application/json' })
             expect(response[2]).to eq([''])
           end
+
+          it 'passes raw binary content through without JSON-encoding it (e.g. File action result)' do
+            binary = String.new("%PDF-1.4\n%\xE2\xE3\xCF\xD3\n", encoding: 'ASCII-8BIT')
+            result = {
+              status: 200,
+              headers: { 'Content-Type' => 'application/pdf' },
+              content: binary,
+              raw: true
+            }
+
+            response = route.send(:build_rails_response, result)
+
+            expect(response[0]).to eq(200)
+            expect(response[1]['Content-Type']).to eq('application/pdf')
+            expect(response[2]).to eq([binary])
+            expect(response[2].first.encoding.name).to eq('ASCII-8BIT')
+          end
         end
 
         context 'when result is not a Hash with :status key' do