tonhowtf/omniget · error

external_data_cache: failed to create

Error message

external_data_cache: failed to create {}: {}

What it means

After resolving the base cache directory, external_data_cache builds base/external-cache/<plugin_id>/<namespace> and calls std::fs::create_dir_all. Any OS-level failure (permissions, read-only filesystem, name issues) is wrapped with the directory path and the io error text. The plugin then cannot store external data.

Solutions

  1. Read the wrapped OS error: PermissionDenied → fix ownership of the cache base dir; ReadOnly/StorageFull → remount or free space.
  2. Ensure the base cache directory is writable by the user running the app (chown/chmod on Linux, folder ACLs on Windows).
  3. Sanitize/limit plugin_id and namespace length so the full path stays under filesystem limits.
  4. In portable mode, move the app to a writable location.

Example fix

// before (failing)
std::fs::create_dir_all("/home/otheruser/.cache/wtf.tonho.omniget/external-cache/myplugin/data")
// after
sudo chown -R $USER ~/.cache/wtf.tonho.omniget
# or in code: fall back to a writable dir on error
Defensive patterns

Strategy: try-catch

Validate before calling

fn cache_base_writable(base: &std::path::Path) -> bool {
    base.exists() || std::fs::create_dir_all(base).is_ok()
}

Try / catch

match host.external_data_cache(plugin_id, ns) {
    Ok(dir) => store(dir),
    Err(e) => {
        log::error!("cache dir unavailable: {e}"); // includes path + OS reason
        // degrade: run plugin without external cache
    }
}

Prevention

When it happens

Trigger: create_dir_all fails because a parent directory is not writable, the disk is read-only/full, the path component derived from plugin_id/namespace is invalid on the filesystem, or an antivirus/ACL blocks creation.

Common situations: Read-only app dir in portable mode (app on a USB stick mounted read-only); Linux cache dir owned by another user after running once with sudo; Windows path length limits with long plugin ids/namespaces; disk full.

Understand the failure class

Background: mkdir permission denied (EACCES): failed to create directory errors explained — this error's family across 32 libraries.

Related errors

AI-assisted analysis of tonhowtf/omniget@8600b91f42 (2026-09-12). Data as JSON: /api/errors/8132b41818d62922. Report an issue: GitHub.

Appendix: source

Thrown at src-tauri/src/plugin_host.rs:144

        // portable installs keep every file next to the app, so the cache
        // lives under the app data dir instead of the OS cache dir
        let base = if std::env::var("OMNIGET_PORTABLE").is_ok() {
            omniget_core::core::paths::app_data_dir()
                .ok_or_else(|| anyhow::anyhow!("external_data_cache: app data dir unavailable"))?
                .join("cache")
        } else {
            dirs::cache_dir()
                .ok_or_else(|| {
                    anyhow::anyhow!(
                        "external_data_cache: OS cache dir unavailable on this platform"
                    )
                })?
                .join("wtf.tonho.omniget")
        };
        let dir = base.join("external-cache").join(plugin_id).join(namespace);
        std::fs::create_dir_all(&dir).map_err(|e| {
            anyhow::anyhow!(
                "external_data_cache: failed to create {}: {}",
                dir.display(),
                e
            )
        })?;
        Ok(dir)
    }

    fn get_cookie_file(&self, domain: &str, account: Option<&str>) -> Option<PathBuf> {
        crate::cookies::account_path_for_consumer(domain, account)
    }

    fn cookie_status(&self, domain: &str) -> omniget_plugin_sdk::CookieStatus {
        let registry = crate::cookies::load_registry();
        let root = crate::cookies::root_domain_of(domain);
        let bucket = match registry.buckets.get(&root) {
            Some(b) => b,
            None => return omniget_plugin_sdk::CookieStatus::Missing,

View on GitHub (pinned to 8600b91f42)