BoundaryML/baml · error · anyhow::Error

Failed to read file

Error message

Failed to read file {}: {}

What it means

BamlProject.load_files throws this when std::fs::read_to_string fails for a workspace file, wrapping the path and the OS error. The file was found by the directory walk but could not be read as UTF-8 text — usually due to permissions, the file being deleted between listing and reading, or binary/invalid-UTF-8 content.

Solutions

1. Restore read permission on the file reported in the error (chmod +r or fix ownership)
2. Re-run the operation after concurrent writers (git checkout, build) finish — the file may have disappeared mid-scan
3. Convert or exclude non-UTF-8/binary files from the workspace directory
4. Check the file still exists; recreate it from version control if deleted

Example fix

// before
-rw------- prompt.baml   # read fails for other users
// after
$ chmod 644 prompt.baml

// Pre-check before the server loads files:
match std::fs::read_to_string(&path) {
    Ok(_) => {},
    Err(e) => eprintln!("Unreadable file {}: {e}", path.display()),
}

match project.load_files() {
    Err(e) if e.to_string().starts_with("Failed to read file") => {
        eprintln!("Fix permissions/encoding for the reported file, then retry: {e}");
    }
    r => r,
}

When it happens

Trigger: load_files() reading a gathered file that has no read permission, vanished after gather_files ran (race with git checkout/build tools), or contains invalid UTF-8 (read_to_string rejects it).

Common situations: Editor watching a repo while a branch switch deletes files mid-scan; files with restrictive permissions (root-owned, 000 modes); binary files or files in non-UTF-8 encodings inside the watched directory.

Understand the failure class

Background: "failed to read file", EACCES, ENOENT and "could not read <path>" errors: when a program can't read a file from disk — this error's family across 49 libraries.

Related errors

• Failed to gather files from directory
• a source root already exists at this path
• BAML Generate failed - Project has errors.
• blob path has no parent
• cannot determine directory of current executable

AI-assisted analysis of BoundaryML/baml@bd85ce9dee (2026-09-12). Data as JSON: /api/errors/97b84ec925d6e2a4. Report an issue: GitHub.

Appendix: source

Thrown at engine/language_server/src/baml_project/mod.rs:288

            anyhow::anyhow!(
                "Failed to gather files from directory {}: {}",
                self.root_dir_name.display(),
                e
            )
        })?;
        let workspace_files = workspace_file_paths
            .into_iter()
            .map(|file_path| {
                let document_key = DocumentKey::from_path(&self.root_dir_name, &file_path)
                    .map_err(|e| {
                        anyhow::anyhow!(
                            "Failed to create document key for file {}: {}",
                            file_path.display(),
                            e
                        )
                    })?;
                let contents = std::fs::read_to_string(&file_path).map_err(|e| {
                    anyhow::anyhow!("Failed to read file {}: {}", file_path.display(), e)
                })?;
                let text_document = TextDocument::new(contents, 0);
                Ok((document_key, text_document))
            })
            .collect::<anyhow::Result<HashMap<_, _>>>()?;

        let project_files = workspace_files.clone();

        self.files = project_files;
        Ok(workspace_files)
    }

    pub fn list_generators(
        &mut self,
        feature_flags: &[String],
    ) -> Result<Vec<BamlGeneratorConfig>, &str> {
        let runtime = self.runtime(HashMap::new(), feature_flags);
        if let Ok(runtime) = runtime {

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