tauri-apps/tauri · error

failed to decode icon {}: {}

Error message

failed to decode icon {}: {}

What it means

Compile-time panic in tauri-codegen's new_ico. The ICO container parsed successfully (IconDir::read) but decoding its first entry via entry.decode() failed, i.e. the embedded bitmap/PNG payload inside the ICO is invalid or unsupported, so RGBA data cannot be extracted for embedding.

Source

Thrown at crates/tauri-codegen/src/image.rs:60

    let buf = Self::open(icon);
    Cached::try_from(buf).map(|cache| Self {
      cache,
      root: root.clone(),
      format: IconFormat::Raw,
    })
  }

  /// Cache an ICO icon as RGBA data, see [`ImageFormat::Image`].
  pub fn new_ico(root: &TokenStream, icon: &Path) -> EmbeddedAssetsResult<Self> {
    let buf = Self::open(icon);

    let icon_dir = ico::IconDir::read(Cursor::new(&buf))
      .unwrap_or_else(|e| panic!("failed to parse icon {}: {}", icon.display(), e));

    let entry = &icon_dir.entries()[0];
    let rgba = entry
      .decode()
      .unwrap_or_else(|e| panic!("failed to decode icon {}: {}", icon.display(), e))
      .rgba_data()
      .to_vec();

    Cached::try_from(rgba).map(|cache| Self {
      cache,
      root: root.clone(),
      format: IconFormat::Image {
        width: entry.width(),
        height: entry.height(),
      },
    })
  }

  /// Cache a PNG icon as RGBA data, see [`ImageFormat::Image`].
  pub fn new_png(root: &TokenStream, icon: &Path) -> EmbeddedAssetsResult<Self> {
    let buf = Self::open(icon);
    let decoder = png::Decoder::new(Cursor::new(&buf));
    let mut reader = decoder

View on GitHub (pinned to 52e4b6e71d)

Solutions

1. Regenerate icons from source with `npx tauri icon app-icon.png`, which emits well-formed multi-size ICO/PNGs
2. Re-export the ICO from a mainstream tool (GIMP, ImageMagick) including standard sizes (16/32/48/256)
3. Validate the file decodes before building: `magick identify icon.ico` or `pngcheck` on the payload

Example fix

# before
# icon.ico parses but entry payload is corrupt -> panic: failed to decode icon

# after
npx tauri icon ./app-icon.png   # regenerates decodable icon.ico
cargo build                    # codegen succeeds

#!/usr/bin/env bash
# prove every .ico decodes end-to-end before the Rust build
for ico in src-tauri/icons/*.ico; do magick identify "$ico" >/dev/null || { echo "undecodable icon: $ico"; exit 1; }; done

When it happens

Trigger: An ICO whose directory header is fine but whose entry payload is corrupt: malformed BMP header, zero width/height, unsupported bit depth, or a truncated image stream produced by a buggy icon converter.

Common situations: ICOs exported by niche online converters; files damaged in transfer or by partial git checkouts; icon variants with exotic compression the ico crate cannot decode.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• failed to parse icon {}: {}
• The `frontendDist` configuration is set to `{path:?}` but th
• failed to read plist {}: {}
• The isolation application path is set to `{dir:?}` but it do
• The isolation application does not contain a file setting th

AI-assisted analysis of tauri-apps/tauri@52e4b6e71d (2026-08-20). Data as JSON: /api/errors/05726f4c09634c40. Report an issue: GitHub.