Failed to canonicalize `WRY_ANDROID_KOTLIN_FILES_OUT_DIR`…

Error message

Failed to canonicalize `WRY_ANDROID_KOTLIN_FILES_OUT_DIR` path {kotlin_out_dir:?}

What it means

After reading `WRY_ANDROID_KOTLIN_FILES_OUT_DIR` on Android builds, the tauri build script canonicalizes the path to a clean absolute path. If the directory doesn't exist or can't be resolved, the build script panics. The tauri CLI normally creates this directory before invoking cargo, so its absence signals a broken mobile build setup.

Solutions

Rebuild via `cargo tauri android build` / `cargo tauri android dev` so the CLI recreates the Kotlin files output directory.
Run `cargo tauri android init` to regenerate a missing src-tauri/gen/android directory.
Verify the WRY_ANDROID_KOTLIN_FILES_OUT_DIR value points to an existing directory (create it if missing).
Clean and rebuild from the project root if the project was moved, so stale absolute paths are refreshed.

Example fix

// before: gen/android deleted manually
rm -rf src-tauri/gen/android && cargo build --target aarch64-linux-android
// after
cargo tauri android init && cargo tauri android build

Defensive patterns

Strategy: validation

Validate before calling

# verify kotlin out dir before android build
[ -d "$WRY_ANDROID_KOTLIN_FILES_OUT_DIR" ] || cargo tauri android init

Prevention

Don't delete or move src-tauri/gen/android manually
Re-run `cargo tauri android init` after restructuring the project
Build via the tauri CLI which creates the output directory before invoking cargo
Clean stale cargo caches after moving a project on disk

When it happens

Trigger: `main()` in build.rs calls `PathBuf::from(kotlin_out_dir).canonicalize()`; the env var points to a nonexistent or inaccessible directory because the build wasn't launched via `tauri android build/dev`, or the gen/android directory was deleted/moved.

Common situations: Deleting or relocating `src-tauri/gen/android`; running the android target outside the tauri CLI; stale cargo caches referencing an old output dir; path casing/drive issues on Windows after moving the project.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

AI-assisted analysis of tauri-apps/tauri@460ec35447 (2026-09-18). Data as JSON: /api/errors/f6d4e7cf69ddec64. Report an issue: GitHub.

Appendix: source

Thrown at crates/tauri/build.rs:291

  if is_tauri_workspace && target_os == "windows" && target_env.is_some_and(|trgt| trgt == "msvc") {
    embed_manifest_for_tests();
  }

  if target_os == "android" {
    fn env_var(var: &str) -> String {
      std::env::var(var).unwrap_or_else(|_| {
        panic!("`{var}` is not set, which is needed to generate the kotlin files for android.")
      })
    }

    if let Some(kotlin_out_dir) = std::env::var_os("WRY_ANDROID_KOTLIN_FILES_OUT_DIR") {
      let package = env_var("WRY_ANDROID_PACKAGE");
      let library = env_var("WRY_ANDROID_LIBRARY");

      let kotlin_out_dir = PathBuf::from(&kotlin_out_dir)
        .canonicalize()
        .unwrap_or_else(move |_| {
          panic!(
            "Failed to canonicalize `WRY_ANDROID_KOTLIN_FILES_OUT_DIR` path {kotlin_out_dir:?}"
          )
        });

      let kotlin_files_path =
        PathBuf::from(env_var("CARGO_MANIFEST_DIR")).join("mobile/android-codegen");
      println!("cargo:rerun-if-changed={}", kotlin_files_path.display());
      let kotlin_files =
        fs::read_dir(kotlin_files_path).expect("failed to read Android codegen directory");

      for file in kotlin_files {
        let file = file.unwrap();

        let content = fs::read_to_string(file.path())
          .expect("failed to read kotlin file as string")
          .replace("{{package}}", &package)
          .replace("{{library}}", &library);

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