File ${path} is encoded as UTF-32 LE, which is not supported

Error message

File ${path} is encoded as UTF-32 LE, which is not supported. Please convert it to UTF-8.

What it means

`decodeBufferAsUtf8` in the windmill CLI checks a file's byte-order mark (BOM) before decoding it as UTF-8. Files saved as UTF-32 LE (BOM FF FE 00 00) are rejected outright because the tooling only supports UTF-8 (with optional UTF-8 BOM).

Source

Thrown at cli/src/utils/utils.ts:139

}

export async function generateHash(content: string): Promise<string> {
  const messageBuffer = new TextEncoder().encode(content);
  return await generateHashFromBuffer(messageBuffer);
}

export async function generateHashFromBuffer(
  content: BufferSource
): Promise<string> {
  const hashBuffer = await crypto.subtle.digest("SHA-256", content);
  return Buffer.from(hashBuffer).toString("hex");
}

function decodeBufferAsUtf8(buf: Buffer, path: string | URL): string {
  if (buf.length >= 2) {
    if (buf[0] === 0xff && buf[1] === 0xfe) {
      if (buf.length >= 4 && buf[2] === 0x00 && buf[3] === 0x00) {
        throw new Error(
          `File ${path} is encoded as UTF-32 LE, which is not supported. Please convert it to UTF-8.`
        );
      }
      throw new Error(
        `File ${path} is encoded as UTF-16 LE, which is not supported. Please convert it to UTF-8.`
      );
    }
    if (buf[0] === 0xfe && buf[1] === 0xff) {
      throw new Error(
        `File ${path} is encoded as UTF-16 BE, which is not supported. Please convert it to UTF-8.`
      );
    }
    if (buf.length >= 4 && buf[0] === 0x00 && buf[1] === 0x00 && buf[2] === 0xfe && buf[3] === 0xff) {
      throw new Error(
        `File ${path} is encoded as UTF-32 BE, which is not supported. Please convert it to UTF-8.`
      );
    }
  }

View on GitHub (pinned to e474e8803c)

Solutions

Re-save the file as UTF-8 (VS Code: 'Save with Encoding' → UTF-8)
Convert in place: `iconv -f UTF-32LE -t UTF-8 file > file.tmp && mv file.tmp file`
On PowerShell: `Get-Content file | Set-Content -Encoding utf8 file`

Example fix

// before (PowerShell)
"content" | Out-File script.yaml -Encoding UTF32
// after
"content" | Out-File script.yaml -Encoding utf8BOM

Defensive patterns

Strategy: validation

Validate before calling

const fs = require('fs');
function assertNotUtf32Le(path) {
  const b = fs.readFileSync(path).subarray(0, 4);
  if (b[0] === 0xff && b[1] === 0xfe && b[2] === 0x00 && b[3] === 0x00)
    throw new Error(`${path} is UTF-32 LE; convert to UTF-8 first`);
}

Type guard

function isUtf32Le(buf) {
  return buf.length >= 4 && buf[0] === 0xff && buf[1] === 0xfe && buf[2] === 0x00 && buf[3] === 0x00;
}

Try / catch

try {
  const content = await readTextFile(path);
} catch (e) {
  if (String(e.message).includes('UTF-32 LE')) console.error('Convert the file to UTF-8 (iconv -f UTF-32LE -t UTF-8).');
  else throw e;
}

Prevention

Configure editors and shell redirections to write UTF-8 (PowerShell: -Encoding utf8)
Check file encodings with `file <path>` before feeding files to the CLI
Avoid legacy Windows 'Unicode'/'UTF-32' save options in Notepad/PowerShell 5

When it happens

Trigger: Reading any file via `readTextFile`/`readTextFileSync` (e.g. a YAML script or flow definition) whose first bytes are FF FE 00 00.

Common situations: Files created or re-saved by Windows Notepad or PowerShell (`Out-File`) writing UTF-32; files converted between encodings incorrectly.

Related errors

AI-assisted analysis of windmill-labs/windmill@e474e8803c (2026-09-03). Data as JSON: /api/errors/c571e36ae75b3d87. Report an issue: GitHub.