tauri-apps/tauri · error

failed to read capabilities

Error message

failed to read capabilities

What it means

Thrown at build time when the generated capabilities file (CAPABILITIES_FILE_NAME, e.g. capabilities.json) exists in the build output dir but cannot be read with `std::fs::read_to_string`. As with the manifest map, existence was just checked, so failure implies permission problems, a race where the file vanished, or path/type issues.

Solutions

1. Delete the stale capabilities file / `cargo clean` and rebuild.
2. Fix permissions or rebuild as the user that owns the generated files.
3. Avoid parallel builds sharing one target directory.
4. Re-run the tauri CLI to regenerate the capabilities file.

Example fix

# before: unreadable generated capabilities file
rm -f src-tauri/target/*/build/*/out/capabilities.json
cargo tauri build

const fs = require('fs');
// pre-build check: generated capabilities file, if present, must be readable
const candidates = ['src-tauri/target/dev/build', 'src-tauri/target/release/build'];
for (const dir of candidates) {
  if (!fs.existsSync(dir)) continue;
  for (const f of findRec(dir, 'capabilities.json')) {
    try { fs.accessSync(f, fs.constants.R_OK); } catch { console.error(`unreadable: ${f} — delete it or fix permissions`); }
  }
}

When it happens

Trigger: Running `tauri build`/`tauri dev` when capabilities.json exists in the out dir but is unreadable: ownership/permission mismatch from a prior build as another user, deleted between check and read, or concurrent builds.

Common situations: CI runners reusing cached target dirs with different users; concurrent dev/build invocations; antivirus or sync tools locking the file.

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 read plugin manifest map
• failed to read plugin global API script paths
• unable to find isolation file
• embedded file asset has no parent
• failed to canonicalize global API script path

AI-assisted analysis of tauri-apps/tauri@460ec35447 (2026-09-18). Data as JSON: /api/errors/15e53693131caf34. Report an issue: GitHub.

Appendix: source

Thrown at crates/tauri-codegen/src/context.rs:407

        key: #key.into(),
        crypto_keys: std::boxed::Box::new(::tauri::utils::pattern::isolation::Keys::new().expect("unable to generate cryptographically secure keys for Tauri \"Isolation\" Pattern")),
      })
    }
  };

  let acl_file_path = out_dir.join(ACL_MANIFESTS_FILE_NAME);
  let acl: BTreeMap<String, Manifest> = if acl_file_path.exists() {
    let acl_file =
      std::fs::read_to_string(acl_file_path).expect("failed to read plugin manifest map");
    serde_json::from_str(&acl_file).expect("failed to parse plugin manifest map")
  } else {
    Default::default()
  };

  let capabilities_file_path = out_dir.join(CAPABILITIES_FILE_NAME);
  let capabilities_from_files = if capabilities_file_path.exists() {
    let capabilities_json =
      std::fs::read_to_string(&capabilities_file_path).expect("failed to read capabilities");
    serde_json::from_str(&capabilities_json).expect("failed to parse capabilities")
  } else {
    Default::default()
  };
  let capabilities = get_capabilities(
    &config,
    capabilities_from_files,
    additional_capabilities.as_deref(),
  )
  .unwrap();

  let resolved = Resolved::resolve(&acl, capabilities, target).expect("failed to resolve ACL");

  let acl_tokens = map_lit(
    quote! { ::std::collections::BTreeMap },
    &acl,
    str_lit,
    identity,

View on GitHub (pinned to 460ec35447)