# Angular Native Federation ERR_INVALID_ARG_VALUE Bug
Hey there, fellow Angular developers! If you've been diving into the exciting world of **module federation** with the latest Angular CLI and **@angular-architects/native-federation**, you might have bumped into a rather pesky error: `TypeError [ERR_INVALID_ARG_VALUE]: The argument 'filename' must be a file URL object, file URL string, or absolute path string. Received './'`. This error typically pops up during the **building federation artifacts** step, especially when you're also integrating **Tailwind CSS v4**. It's a bit of a head-scratcher, especially when you're expecting a smooth build process. Let's break down what's happening and how we can navigate this issue.
## Understanding the ERR_INVALID_ARG_VALUE Error in Native Federation Builds
This particular error, `ERR_INVALID_ARG_VALUE`, often signals a problem with how a file path or a filename is being interpreted by Node.js. In the context of **building federation artifacts** with **Native Federation** and the newer **Angular build system** (which leverages esbuild), the issue seems to stem from how PostCSS, a tool used by Tailwind CSS for processing styles, is trying to resolve its configuration or input files. The message `Received './'` is a strong clue that the build process is attempting to use a relative path (`./`) where an absolute path or a proper file URL is expected. This can happen for a variety of reasons, including misconfigurations in `postcss.config.js`, issues with how plugins are chained, or even conflicts between different versions of dependencies like `@angular/build`, `postcss`, and `tailwindcss`.
When you're setting up **module federation** for your Angular projects, especially with tools like Native Federation, the build process becomes quite intricate. It involves multiple steps to bundle your application, externalize dependencies, and generate the necessary metadata for other applications to consume. If you're also using **Tailwind CSS v4**, which has its own build pipeline that often integrates with PostCSS, these layers of processing can introduce potential conflicts. The error occurs specifically at the `Building federation artefacts` stage, which means the problem is likely happening when Native Federation is trying to integrate the processed stylesheets into the final artifact. The `StylesheetPluginFactory.initPostcss` function mentioned in the stack trace points directly to an issue within the stylesheet processing pipeline managed by `@angular/build`.
It's crucial to ensure that all your dependencies are aligned, especially when dealing with cutting-edge features like the new Angular CLI build system and the latest versions of CSS tooling. Incompatibilities or subtle version mismatches can lead to these kinds of `ERR_INVALID_ARG_VALUE` errors. The fact that the error mentions `./` suggests that a part of the PostCSS configuration or a plugin within it is not correctly resolving the current directory as a file path. This could be due to how esbuild is invoking PostCSS or how Native Federation is orchestrating the build.
To tackle this, we need to look closely at the project's configuration files. This includes `angular.json`, `native-federation.config.js`, and any PostCSS configuration files. Ensuring that paths are correctly specified and that dependencies are compatible is key to resolving this building federation artifacts issue. We’ll explore specific steps to address this in the following sections, aiming for a successful build and serve experience.
## Reproducing the Bug: Step-by-Step Guide
To effectively address the `ERR_INVALID_ARG_VALUE` error when **building federation artifacts** with **Native Federation** and the latest Angular, it's essential to have a reliable way to reproduce the bug. The provided GitHub repository, `[https://github.com/Dung288-806/angular-mfe-remote.git](https://github.com/Dung288-806/angular-mfe-remote.git)`, serves as an excellent starting point for anyone experiencing this issue. Following these steps will allow you to replicate the exact scenario that triggers the error, which is a vital first step in debugging and finding a solution.
Here’s a breakdown of the reproduction process based on the provided details:
1. **Install Native Federation:** The first prerequisite is to correctly integrate **Native Federation** into your Angular project. This typically involves running installation commands and potentially some initial configuration. The repository assumes this step has been completed successfully.
2. **Configure Federation for the Project:** Once installed, **Native Federation** needs to be configured within your Angular application. This usually involves creating or modifying a configuration file (like `native-federation.config.js`) where you define the share scopes, exposes, and remotes. The repository linked should already have this setup in place, demonstrating how it's intended to be configured.
3. **Run the Build Federation Artifacts Command:** The critical step where the error manifests is when you execute the build command for federation artifacts. For Angular projects, this is typically `ng build`. However, when **module federation** is involved, the build process is enhanced to create the necessary federation artifacts. The repository's setup should trigger this enhanced build.
4. **Observe the Error:** Upon running `ng build`, you should see output indicating that the build process is starting, likely with a message like `INFO Building federation artefacts`. Shortly after this, the `TypeError [ERR_INVALID_ARG_VALUE]` will appear, halting the build. The error message will include details about an invalid filename argument, specifically `Received './'`, and will point to a file within the `@angular/build` package, such as `stylesheet-plugin-factory.js`.
**The Environment:** The problem is reported to occur with:
* **Node.js versions:** v24.12.0 or V22.x. These are relatively recent versions of Node.js.
* **Angular versions:** The issue is specifically tied to the latest Angular versions, indicated by the `@angular/cli`, `@angular/build`, and core Angular packages being around `^21.0.0` or `^21.0.3`.
* **Native Federation:** Versions like `@softarc/native-federation-node: ^3.3.4` and `@angular-architects/native-federation: ^21.0.0`.
* **Tailwind CSS:** The problem seems to be exacerbated or specifically triggered when using **Tailwind CSS v4** (`^4.1.12`), along with its PostCSS dependencies (`postcss: ^8.5.3`, `@tailwindcss/postcss: ^4.1.12`).
By following these steps and using the provided repository, you can reliably reproduce the `ERR_INVALID_ARG_VALUE` error. This consistency is invaluable for testing potential fixes and understanding the root cause of the problem during the **building federation artifacts** process.
## Debugging the ERR_INVALID_ARG_VALUE: Investigating Dependencies and Configurations
When faced with the `ERR_INVALID_ARG_VALUE` error during the **building federation artifacts** phase with **Native Federation** and the latest Angular, the most effective approach involves a deep dive into your project's configurations and the intricate web of dependencies. The error message, `TypeError [ERR_INVALID_ARG_VALUE]: The argument 'filename' must be a file URL object, file URL string, or absolute path string. Received './'`, combined with the stack trace pointing to `@angular/build/src/tools/esbuild/stylesheets/stylesheet-plugin-factory.js`, strongly suggests an issue with how stylesheets, particularly those processed by **Tailwind CSS v4** via PostCSS, are being handled by the new Angular build pipeline (which uses esbuild).
Let's break down the areas to investigate:
1. **Dependency Version Alignment:** This is often the most common culprit. The error occurs with specific versions of Node.js (v24.12.0 or V22.x), Angular (`^21.0.0`), `@angular/build` (`^21.0.3`), and importantly, **Tailwind CSS v4** (`^4.1.12`) and its PostCSS ecosystem (`postcss: ^8.5.3`).
* **Check for Incompatibilities:** Newer versions of Angular CLI and `@angular/build` are designed to work with specific versions of PostCSS and related tools. **Tailwind CSS v4** might introduce changes that are not yet fully compatible with the versions of PostCSS or the way `@angular/build` expects them to be configured. It’s worth checking the release notes for both Tailwind CSS and `@angular/build` for any known compatibility issues.
* **NPM/Yarn Audit:** Run `npm audit` or `yarn audit` to identify any high-severity vulnerabilities or potential dependency conflicts. Sometimes, transitive dependencies can cause unexpected behavior.
* **Peer Dependencies:** Pay close attention to peer dependencies. If `@angular/build` expects a certain range of `postcss` versions, and Tailwind CSS requires a different, incompatible one, this can lead to the `ERR_INVALID_ARG_VALUE` error.
2. **PostCSS and Tailwind CSS Configuration:** The error specifically mentions stylesheet processing. Your `postcss.config.js` file (or equivalent configuration) is a prime suspect.
* **Path Resolution:** The `Received './'` error suggests that PostCSS or one of its plugins is trying to resolve a file path relative to the current directory, but the context in which it's being called by esbuild doesn't provide the expected base path. Ensure that any paths defined in your `postcss.config.js`, especially for input/output files or plugin configurations, are absolute or correctly resolved.
* **Tailwind CSS v4 Specifics:** Tailwind CSS v4 might have different configuration options or plugin structures compared to previous versions. Ensure your `tailwind.config.js` and `postcss.config.js` are set up according to the latest Tailwind v4 documentation.
* **Plugin Order:** The order of plugins in PostCSS can sometimes matter. If there are custom plugins or specific configurations related to Native Federation or Angular's build process, ensure they are ordered correctly.
3. **Native Federation Configuration (`native-federation.config.js`):** While less likely to directly cause a `filename` error in PostCSS, misconfigurations here can indirectly affect how assets and styles are processed.
* **Asset Handling:** Review how your `native-federation.config.js` handles assets or custom webpack/esbuild configurations. Sometimes, style processing is entangled with asset bundling.
4. **Angular Build Configuration (`angular.json`):** Check your `angular.json` file for any specific build configurations related to styles or PostCSS.
* **StylePreprocessorOptions:** Ensure there are no conflicting configurations or incorrect paths specified under the `build` or `test` configurations, especially within `stylePreprocessorOptions`.
5. **Node.js Environment:** Although the error is likely in the build logic, ensure your Node.js environment is clean. Sometimes, global installations or environment variables can interfere.
**A Potential Fix Direction:** Given the error points to `@angular/build`'s stylesheet processing, the most promising avenue is to investigate the interaction between **Tailwind CSS v4**, PostCSS, and the esbuild integration within `@angular/build`. You might need to explicitly define the `cwd` (current working directory) for PostCSS, or ensure that Tailwind's PostCSS plugin is correctly initialized with the project's root directory. Downgrading PostCSS or Tailwind to versions known to be compatible with your specific Angular build setup might be a temporary workaround while a more permanent fix is developed or documented.
Ultimately, debugging this **ERR_INVALID_ARG_VALUE** requires careful examination of these interconnected components. The goal is to ensure that when the Angular build process invokes PostCSS for **building federation artifacts**, all file paths are resolved correctly, preventing the `Received './'` error and allowing your module federation setup to function as expected.
## Potential Solutions and Workarounds for the Native Federation Build Error
Encountering the `TypeError [ERR_INVALID_ARG_VALUE]: Received './'` error when **building federation artifacts** with **Native Federation**, the latest Angular, and **Tailwind CSS v4** can be frustrating. However, several strategies and workarounds can help you overcome this hurdle and get your module federation setup working smoothly. The key is often in aligning dependency versions, adjusting configurations, or providing explicit paths where the build process might be struggling.
Here are some potential solutions and workarounds:
1. **Version Pinning and Downgrading:**
* **PostCSS and Tailwind CSS:** The most direct approach is often to identify versions of `postcss` and `tailwindcss` that are known to be compatible with your specific version of `@angular/build` and the Angular CLI. Since the error occurs during stylesheet processing involving Tailwind and PostCSS, try downgrading `postcss` and `tailwindcss` to versions that were stable around the time your Angular version was released. Check the release notes or community forums for `@angular/build` and Tailwind CSS for recommended version combinations.
* **Example:** You might try pinning `postcss` to `^8.4.0` or a similar stable version if `^8.5.3` is causing issues. Similarly, if `tailwindcss@^4.1.12` is the problem, consider trying an earlier v4 patch or even a v3 version temporarily to see if the issue resolves.
2. **Explicitly Configure PostCSS Paths:**
* The error `Received './'` suggests that PostCSS is not correctly resolving its working directory. You might need to explicitly tell PostCSS where to find its configuration or how to resolve paths.
* **`postcss.config.js` Modification:** Ensure your `postcss.config.js` file is correctly set up. Sometimes, adding `process.cwd()` or using `path.resolve()` for any path-related options can help.
* **Example:** If you have a configuration like `plugins: [require('tailwindcss'), ...]` , ensure that any plugins that might be sensitive to the current working directory are configured with explicit paths.
3. **Tailwind CSS Configuration Adjustments:**
* **`tailwind.config.js`:** Review your `tailwind.config.js` file. Ensure that the `content` array correctly specifies the files to scan for classes. If there are complex path configurations, simplify them to rule out issues.
* **`purge` option (if applicable/older versions):** If you're accidentally using older configuration options like `purge` instead of `content`, update it to the latest syntax.
4. **Angular Build Configuration (`angular.json`):
* **`stylePreprocessorOptions`:** Double-check your `angular.json`. While less common for PostCSS issues directly, ensure that any `stylePreprocessorOptions` or `style` configurations within your build target are correctly defined and not causing conflicts.
5. **Native Federation Configuration (`native-federation.config.js`):
* **Custom esbuild/Webpack Config:** If you've added custom esbuild or Webpack configurations within your Native Federation setup, review them carefully. Ensure they don't interfere with the default stylesheet processing pipeline of `@angular/build`.
* **Asset Handling:** Verify that your federation configuration isn't inadvertently overriding or mismanaging how CSS assets are processed or included.
6. **Isolate the Issue:**
* **Temporarily Disable Tailwind:** As a diagnostic step, try building your federation artifacts *without* Tailwind CSS and PostCSS configured. If the build succeeds, you've confirmed that the issue lies specifically in the integration of Tailwind/PostCSS with the Angular build and Native Federation. Then, you can reintroduce Tailwind step-by-step.
* **Simplify PostCSS Plugins:** If you have multiple PostCSS plugins, try removing them one by one to identify which plugin might be causing the `ERR_INVALID_ARG_VALUE` error.
7. **Check for Global Dependencies:**
* Ensure you don't have conflicting global installations of `postcss` or `tailwindcss` that might be interfering with project-local versions.
8. **Contribute to the Community/Report Issue:**
* If you've exhausted other options, consider opening a detailed issue on the **Native Federation GitHub repository** or the **Angular Build repository**. Providing the reproduction steps (like the linked GitHub repo) and a clear description of the error is invaluable for the maintainers to investigate and potentially release a fix.
By systematically working through these solutions, you can pinpoint the cause of the `ERR_INVALID_ARG_VALUE` error. Often, the fix involves a specific version alignment or a minor configuration tweak. The goal is to achieve a successful build that allows you to serve your **federation artifacts** without errors.
## Conclusion: Moving Forward with Module Federation and Native Federation
The `TypeError [ERR_INVALID_ARG_VALUE]: Received './'` error encountered during **building federation artifacts** with **Native Federation**, the latest Angular CLI, and **Tailwind CSS v4** highlights a common challenge in modern web development: the intricate interplay between various build tools and libraries. While this specific error might seem daunting, it's a sign that the build pipeline, particularly the stylesheet processing part integrated with esbuild via `@angular/build`, is encountering an unexpected path resolution issue. This often stems from subtle incompatibilities between dependency versions or misconfigurations in how PostCSS, Tailwind CSS, and the Angular build system interact.
We've explored the nature of this error, how to reproduce it using a provided repository, and delved into debugging strategies focusing on dependency alignment and configuration checks. The potential solutions range from pinning specific versions of PostCSS and Tailwind CSS to explicitly configuring paths and simplifying plugin setups. Remember, the key to resolving such issues lies in methodical investigation and understanding the layers involved in your project's build process.
As **module federation** continues to evolve, especially with native solutions like **Native Federation** offering streamlined approaches, staying updated with best practices and being prepared to troubleshoot version conflicts is crucial. The Angular ecosystem is dynamic, and keeping your dependencies in sync, while adopting new features like Tailwind CSS v4, requires vigilance.
If you find yourself stuck, don't hesitate to leverage community resources. Open issues on the relevant GitHub repositories, consult documentation, and share your findings. Often, a collective effort leads to faster resolution and improvements for everyone.
For further reading and deeper insights into module federation and advanced Angular build configurations, consider exploring the official documentation:
* Learn more about **Angular's module federation** capabilities on the **[Angular documentation site](https://angular.io/guide/module-federation)**.
* Dive into the specifics of **Native Federation** and its features on the **[official Native Federation documentation](https://www.native-federation.com/)**.
By understanding the potential pitfalls and actively seeking solutions, you can successfully implement sophisticated architectures like module federation in your Angular applications.
