diff --git a/lib/kamal/cli/main.rb b/lib/kamal/cli/main.rb
index 873cf6657..b07f73de9 100644
--- a/lib/kamal/cli/main.rb
+++ b/lib/kamal/cli/main.rb
@@ -37,13 +37,25 @@ def deploy(boot_accessories: false)
           say "Ensure kamal-proxy is running...", :magenta
           invoke "kamal:cli:proxy:boot", [], invoke_options
 
-          invoke "kamal:cli:accessory:boot", [ "all" ], invoke_options if boot_accessories
+          # Boot non-proxied accessories first to avoid error pages directory validation issues on fresh servers.
+          # Proxied accessories will be booted after app:boot to ensure error pages are available.
+          # The outer deploy lock remains held across both accessory groups and app:boot.
+          if boot_accessories
+            non_proxied_accessories = KAMAL.accessory_names.filter { |name| !KAMAL.accessory(name).running_proxy? }
+            non_proxied_accessories.each { |name| invoke "kamal:cli:accessory:boot", [ name ], invoke_options }
+          end
 
           say "Detect stale containers...", :magenta
           invoke "kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true)
 
           invoke "kamal:cli:app:boot", [], invoke_options
 
+          # Boot proxied accessories after app:boot to ensure error pages directory exists
+          if boot_accessories
+            proxied_accessories = KAMAL.accessory_names.filter { |name| KAMAL.accessory(name).running_proxy? }
+            proxied_accessories.each { |name| invoke "kamal:cli:accessory:boot", [ name ], invoke_options }
+          end
+
           say "Prune old containers and images...", :magenta
           invoke "kamal:cli:prune:all", [], invoke_options
         end
diff --git a/test/cli/main_test.rb b/test/cli/main_test.rb
index 16b2807e2..353258300 100644
--- a/test/cli/main_test.rb
+++ b/test/cli/main_test.rb
@@ -19,8 +19,7 @@ class CliMainTest < CliTestCase
     invoke_options = base_invoke_options
 
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:server:bootstrap", [], invoke_options)
-    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:accessory:boot", [ "all" ], invoke_options)
-    # deploy
+    # deploy (deploy_simple.yml has no accessories, so no accessory:boot invocations expected)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:build:pull", [], invoke_options)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:proxy:boot", [], invoke_options)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true))
@@ -67,8 +66,7 @@ class CliMainTest < CliTestCase
     invoke_options = base_invoke_options(no_cache: true)
 
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:server:bootstrap", [], invoke_options)
-    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:accessory:boot", [ "all" ], invoke_options)
-    # deploy
+    # deploy (deploy_simple.yml has no accessories, so no accessory:boot invocations expected)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:build:deliver", [], invoke_options)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:proxy:boot", [], invoke_options)
     Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true))
@@ -85,6 +83,30 @@ class CliMainTest < CliTestCase
     end
   end
 
+  test "setup with error pages and proxied accessory boots accessories in correct order" do
+    invoke_options = base_invoke_options(config_file: "deploy_with_error_pages_and_accessories.yml")
+    boot_sequence = sequence("boot accessories around app")
+
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:server:bootstrap", [], invoke_options)
+    # Non-proxied accessory (mysql) should be booted first
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:accessory:boot", [ "mysql" ], invoke_options).in_sequence(boot_sequence)
+    # deploy
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:build:deliver", [], invoke_options)
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:proxy:boot", [], invoke_options)
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:app:stale_containers", [], invoke_options.merge(stop: true))
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:app:boot", [], invoke_options).in_sequence(boot_sequence)
+    # Proxied accessory (cache) should be booted after app:boot to ensure error pages directory exists
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:accessory:boot", [ "cache" ], invoke_options).in_sequence(boot_sequence)
+    Kamal::Cli::Main.any_instance.expects(:invoke).with("kamal:cli:prune:all", [], invoke_options)
+
+    run_command("setup", config_file: "deploy_with_error_pages_and_accessories.yml").tap do |output|
+      assert_match /Ensure Docker is installed.../, output
+      assert_match /Build and push app image/, output
+      assert_match /Ensure kamal-proxy is running/, output
+      assert_match /Prune old containers and images/, output
+    end
+  end
+
   test "deploy" do
     with_test_secrets("secrets" => "DB_PASSWORD=secret") do
       invoke_options = base_invoke_options(verbose: true)
diff --git a/test/fixtures/deploy_with_error_pages_and_accessories.yml b/test/fixtures/deploy_with_error_pages_and_accessories.yml
new file mode 100644
index 000000000..fc29a6bd5
--- /dev/null
+++ b/test/fixtures/deploy_with_error_pages_and_accessories.yml
@@ -0,0 +1,25 @@
+service: app
+image: dhh/app
+servers:
+  - "1.1.1.1"
+registry:
+  username: user
+  password: pw
+builder:
+  arch: amd64
+
+accessories:
+  mysql:
+    image: mysql:5.7
+    host: 1.1.1.1
+    port: 3306
+  cache:
+    image: redis:7-alpine
+    host: 1.1.1.1
+    port: 6379:6379
+    proxy:
+      host: cache.example.com
+      path_prefix: "/cache"
+      app_port: 6379
+
+error_pages_path: public