CLI 3.84.1+ Regression: "Unknown tag 'schema'" for app_block with require_remote_ui

I have reproduced the issue on the latest CLI version.

Yes, I am on the latest version

I have searched existing posts and this report is not a duplicate.

Yes, this isn’t a duplicate

In which of these areas are you experiencing a problem?

App

Expected behavior

The Shopify CLI should successfully parse and validate Liquid files containing {% schema %} tags in theme app extension blocks, especially when:

  1. The extension uses require_remote_ui = true in the TOML configuration
  2. The TOML file has settings_schema = { version = 1 } defined in the [[blocks]] section
  3. Both TOML [blocks.schema] and [settings] sections are present alongside the Liquid schema tag

When running shopify app dev --use-localhost or shopify app deploy, the CLI should:

  • Recognize {% schema %} as a valid Liquid tag
  • Parse the schema JSON without errors
  • Allow development server to start or deployment to proceed
  • NOT throw “Unknown tag ‘schema’” errors for valid schema blocks

This configuration worked perfectly in commit de319352417a1d702a02c4f3c9196bd65df063c5 (Dec 11, 2025), confirming this is the expected behavior.

Actual behavior

The Shopify CLI throws a “Liquid syntax error: Unknown tag ‘schema’” error when processing Liquid files that contain {% schema %} tags, even when:

  1. The schema JSON is valid and properly formatted
  2. The configuration matches a previously working setup exactly (commit de319352417a1d702a02c4f3c9196bd65df063c5)
  3. The TOML file has all required sections (require_remote_ui = true, settings_schema = { version = 1 }, [blocks.schema], [settings])
  4. The file structure follows Shopify documentation

When running shopify app dev --use-localhost or shopify app deploy, the CLI:

  • Fails immediately with “Unknown tag ‘schema’” error
  • Prevents the development server from starting
  • Blocks deployment completely
  • Creates a catch-22: removing the schema tag results in “Tag ‘schema’ is missing” error

This is a regression - the exact same files that worked in December 2025 now fail with CLI 3.84.1+.

Reproduction steps

  1. Create a theme app extension with type = "theme_app_extension" in shopify.theme.extension.toml

  2. Configure the TOML file with:

    • [runtime_context] section with require_remote_ui = true
    • [[blocks]] section with type = "app_block" and settings_schema = { version = 1 }
    • [blocks.schema] section with field definitions
    • [settings] section with settings fields
  3. Create a Liquid file in the blocks/ directory (e.g., blocks/chat-widget.liquid)

  4. Add a valid {% schema %} tag with JSON content in the Liquid file:

  5. Run: shopify app dev --use-localhost (or shopify app deploy)

  6. Observe the error: [blocks/chat-widget.liquid] Liquid syntax error (line X): Unknown tag 'schema'

Note: This occurs with Shopify CLI 3.84.1+ (required by Shopify API). The same configuration worked in CLI 3.80.0, but that version is now rejected by Shopify’s API.

Verbose output

shopify app dev --use-localhost --verbose
2025-12-16T06:33:33.460Z: Running command app dev
2025-12-16T06:33:33.464Z: Running system process in background:
  · Command: /opt/homebrew/Cellar/node/24.1.0/bin/node /opt/homebrew/bin/shopify notifications list --ignore-errors
  · Working directory: /Users/makseth/Development/eshopAiCustomerService

2025-12-16T06:33:33.472Z: Notifications to show: 0
2025-12-16T06:33:33.487Z: Port 3458 is free
╭─ error ──────────────────────────────────────────────────────────────────────╮
│                                                                              │
│  Couldn't find an app toml file at                                           │
│  /Users/makseth/Development/eshopAiCustomerService, is this an app           │
│  directory?                                                                  │
│                                                                              │
╰──────────────────────────────────────────────────────────────────────────────╯

2025-12-16T06:33:33.563Z: Running system process:
  · Command: npm prefix
  · Working directory: /Users/makseth/Development/eshopAiCustomerService

2025-12-16T06:33:33.876Z: Obtaining the dependency manager in directory /Users/makseth/Development/eshopAiCustomerService...
2025-12-16T06:33:34.063Z: Getting session store...
2025-12-16T06:33:34.065Z: Getting session store...
2025-12-16T06:33:34.335Z: Request to https://monorail-edge.shopifysvc.com/v1/produce completed in 260 ms
With response headers:
 - x-request-id: 98552325-e759-4017-a592-c0d885701718
    
2025-12-16T06:33:34.336Z: Analytics event sent: {
  "command": "app dev",
  "time_start": 1765866813461,
  "time_end": 1765866813556,
  "total_time": 95,
  "success": false,
  "cli_version": "3.84.1",
  "ruby_version": "",
  "node_version": "24.1.0",
  "is_employee": false,
  "uname": "darwin arm64",
  "env_ci": false,
  "env_plugin_installed_any_custom": false,
  "env_plugin_installed_shopify": "[\"@shopify/cli\"]",
  "env_shell": "zsh",
  "env_device_id": "592ca33f3748b9c82d89b7890d2cf2b42fca6668",
  "env_cloud": "localhost",
  "env_package_manager": "npm",
  "env_is_global": true,
  "env_auth_method": "device_auth",
  "env_is_wsl": false,
  "env_build_repository": "Shopify/cli",
  "cmd_app_warning_api_key_deprecation_displayed": false,
  "cmd_all_timing_network_ms": 0,
  "cmd_all_timing_prompts_ms": 0,
  "cmd_all_launcher": "unknown",
  "cmd_all_topic": "app",
  "cmd_all_plugin": "@shopify/app",
  "cmd_all_verbose": true,
  "cmd_all_path_override": true,
  "cmd_all_path_override_hash": "20407bfaa04cafa65f4741c4143e29525a5e64b6",
  "cmd_app_dependency_installation_skipped": false,
  "cmd_app_reset_used": false,
  "cmd_dev_tunnel_type": "use-localhost",
  "cmd_all_timing_active_ms": 95,
  "cmd_all_exit": "expected_error",
  "user_id": "d05f6ec7-ccb4-4e72-825f-e0685b48f5f8",
  "request_ids": [],
  "args": "--use-localhost --verbose",
  "error_message": "Couldn't find an app toml file at /Users/makseth/Development/eshopAiCustomerService, is this an app directory?",
  "env_plugin_installed_all": "[\"@shopify/cli\"]",
  "metadata": "{\"extraPublic\":{},\"extraSensitive\":{}}"
}
2025-12-16T06:33:34.362Z: Reporting handled error to Bugsnag: Couldn't find an app toml file at /Users/makseth/Development/eshopAiCustomerService, is this an app directory?
2025-12-16T06:33:35.061Z: Running system process:
  · Command: npm prefix
  · Working directory: /Users/makseth/Development/eshopAiCustomerService

2025-12-16T06:33:35.230Z: Obtaining the dependency manager in directory /Users/makseth/Development/eshopAiCustomerService...
2025-12-16T06:33:35.231Z: Getting session store...

Operating system

Mac OS 15.6.1 (24G90)

CLI version

3.84.1

Shell

bash

Nodejs version

v24.1.0

What language and version are you using in your application?

Node.js v24.1.0 (runtime for Shopify CLI)Python 3.13.4 (backend API)TypeScript 5.0.4 (frontend application)React 18.2.0 (frontend UI)Liquid (Shopify templating language in theme app extension)Note: The Shopify CLI is running on Node.js v24.1.0, which is newer than the project’s specified range (^18.20 || ^20.10 || >=21.0.0). This may be a contributing factor to the regression.

This is likely caused by this issue: Liquid syntax error : Unknown tag 'schema' when running shopify app dev

Is there any solution, I am facing the same issue. Yesterday it was working fine. It is stopping dev preview as well.