mastra-ai/mastra · error

Unsupported file type

Error message

Unsupported file type

What it means

readWorkspaceFile only serves regular files; after lstat, anything that is neither a directory nor a regular file (symlinks to non-files, FIFOs, sockets, device nodes) triggers 'Unsupported file type'. The library throws to avoid hanging on special files (e.g. reading a FIFO blocks) or reading meaningless binary device data.

Source

Thrown at mastracode/factory/src/routes/fs.ts:372

    workspacePath: workspace,
    root: safeRoot,
    rootPath: confinedRootPath,
    entries: await listRenderedEntries(confinedRootPath),
  };
}

export async function readWorkspaceFile(root: string, workspacePath: string, path: string): Promise<WorkspaceFile> {
  const safePath = assertRelativePath(path, 'path');
  const relativeRoot = safePath.split('/')[0] ?? '';
  assertApprovedRenderedRoot(relativeRoot);
  const {
    workspace,
    path: confinedPath,
    relativePath,
  } = await confinedWorkspaceRelativePath(root, workspacePath, path);
  const info = await lstat(confinedPath);
  if (info.isDirectory()) throw new Error('Path is a directory');
  if (!info.isFile()) throw new Error('Unsupported file type');

  const bytesToRead = Math.min(info.size, MAX_TEXT_FILE_BYTES);
  const contentBuffer = Buffer.alloc(bytesToRead);
  const handle = await open(confinedPath, 'r');
  try {
    await handle.read(contentBuffer, 0, bytesToRead, 0);
  } finally {
    await handle.close();
  }

  try {
    const content = TEXT_DECODER.decode(contentBuffer);
    return {
      workspacePath: workspace,
      path: relativePath,
      name: relativePath.split('/').pop() ?? relativePath,
      size: info.size,
      updatedAt: info.mtime.toISOString(),

View on GitHub (pinned to 75dd419e61)

Solutions

1. Identify the entry's real type (ls -l shows p for FIFO, s for socket) and remove it if it does not belong in the workspace.
2. If you need its content, have the producer write to a regular file instead of a pipe/socket.
3. Exclude special files from the paths your client requests (filter listing entries by type === 'file').
4. Regenerate the workspace/artifacts so the special file is replaced by a normal file.

Example fix

// before: workspace contains a FIFO
mkfifo debug.log; GET /fs/file?path=debug.log  // → 'Unsupported file type'
// after: produce a regular file
node script.js > debug.log
GET /fs/file?path=debug.log

import { lstat } from 'node:fs/promises';
async function isRegularFile(p: string): Promise<boolean> {
  try {
    const info = await lstat(p);
    return info.isFile();
  } catch {
    return false;
  }
}
// skip the read when isRegularFile(confinedPath) is false

function isRegularFileStats(info: { isFile(): boolean; isDirectory(): boolean }): boolean {
  return info.isFile() && !info.isDirectory();
}

try {
  const file = await readWorkspaceFile(root, ws, path);
} catch (e) {
  if (e instanceof Error && e.message === 'Unsupported file type') {
    // mark entry contentType 'unsupported' / skip it, never retry
    return null;
  }
  throw e;
}

When it happens

Trigger: Calling readWorkspaceFile with a path that resolves to a special filesystem object: a named pipe created by a build tool, a Unix socket in the workspace, a device file bind-mounted into a sandbox, or (via lstat semantics) a non-regular entry exposed by the confinement layer.

Common situations: Workspaces containing build artifacts like .sock pipes or FIFOs; sandboxed session workspaces that expose device nodes; a test fixture accidentally creating a socket where a log file was expected.

Related errors

• Missing required query param: ${label}
• ${label} must be relative
• ${label} escapes workspace
• Path escapes workspace
• Path is a directory

AI-assisted analysis of mastra-ai/mastra@75dd419e61 (2026-08-30). Data as JSON: /api/errors/74d7a18b185ca62d. Report an issue: GitHub.