# Universal Android Debloater Next Generation Troubleshooting: Common Issues and Solutions > Troubleshoot Universal Android Debloater Next Generation with solutions for ADB issues, Knox blocks, and self-update errors. Learn how to enable debug logging for faster resolution. - Repository: [Universal-Debloater-Alliance/universal-android-debloater-next-generation](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation) - Tags: troubleshooting-guide - Published: 2026-06-18 --- **Universal Android Debloater Next Generation (UAD-NG) troubleshooting typically involves resolving ADB connectivity failures, permission restrictions like Samsung Knox blocks, cross-user package restoration issues, and self-update errors by examining the Rust core crate's error handling paths and enabling verbose logging with `RUST_LOG=debug`.** Universal Android Debloater Next Generation is architected as three Rust crates—`uad-core`, `uad-gui`, and `uad-cli`—that communicate with Android devices via ADB to remove pre-installed bloatware. Most operational failures originate in the core crate's synchronization logic, where raw ADB errors are captured and translated into user-friendly messages before surfacing in the GUI or CLI. ## Device Detection and ADB Connectivity Issues The most common entry point failure occurs when `uad-core::sync::get_device_model` cannot execute ADB commands, as implemented in lines 20-33 of [`crates/uad-core/src/sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/sync.rs). When this happens, the CLI prints *"no devices/emulators found"* while the GUI displays an infinite loading spinner. **Root cause:** The ADB binary is not in PATH, USB debugging is disabled, or the device lacks authorization. **Troubleshooting steps:** 1. Verify ADB is installed and accessible: `adb version` 2. Enable **USB debugging** on the Android device and authorize the PC when prompted 3. Restart the ADB server: `adb kill-server && adb start-server` 4. Run UAD-NG with debug logging to see exact ADB output: ```bash RUST_LOG=debug uad devices ``` ## Permission-Related Failures and Samsung Knox Restrictions UAD-NG translates raw ADB error strings into actionable messages via `make_friendly_error_message` in [`crates/uad-core/src/sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/sync.rs) (lines 90-138). The GUI surfaces these in an error modal defined in `error_view` within [`crates/uad-gui/src/views/list.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-gui/src/views/list.rs). **Common error patterns and fixes:** - **DELETE_FAILED_USER_RESTRICTED**: Samsung Knox or OEM restrictions block uninstallation. Use `disable` instead of `uninstall`, or disable the Knox security profile in device settings. - **NOT_INSTALLED_FOR_USER**: The package is missing for the selected Android user. Specify the correct user with `--user ` in the CLI or select the appropriate profile in the GUI. - **Shell cannot change component state for null**: Indicates a stale package list. Refresh the package list using `uad update` or the GUI's *Refresh* button. - **Permission denied** or **INSTALL_FAILED_PERMISSION_MODEL_DOWNGRADE**: Requires root privileges or indicates a protected package. Run on a **rooted device** or use **dry-run** mode to verify before proceeding. - **DELETE_FAILED_DEVICE_POLICY_MANAGER**: The package is managed by corporate MDM/EMM. Contact IT admin or switch to a personal profile. ## Cross-User Package Restoration Issues When a package reappears on secondary users after removal from the primary user, `detect_cross_user_behavior` (lines 90-191 of [`crates/uad-core/src/sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/sync.rs)) generates a notification like: *"Detected cross-user restoration: package exists on user 10 (Enabled) after uninstalling from user 0"*. **Diagnostic workflow:** 1. List all users: `uad devices` or `adb shell pm list users` 2. Identify affected packages on specific users: `uad list --state enabled --user 10` 3. Apply actions to all users simultaneously: `uad uninstall com.example.app --user all` ## Self-Update Failures The update subsystem in [`crates/uad-core/src/update.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/update.rs) downloads releases from GitHub. Failures at lines 55-70 (`download_file`) propagate as `SelfUpdateStatus::Failed`, causing the GUI to display *"Failed to check update!"* or the CLI to print *"✗ Failed to update lists from remote, using cached version"*. **Resolution steps:** 1. Verify internet connectivity and GitHub API access: `curl https://api.github.com` 2. Check for **rate limiting** (HTTP 403); if hit, wait one hour or use a different network 3. If automatic updates fail, perform a manual build: ```bash git clone https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation.git cd universal-android-debloater-next-generation cargo build --release -p uad-cli ``` Replace the existing binary with `target/release/uad`. ## Backup and Configuration Errors The GUI's settings view ([`crates/uad-gui/src/views/settings.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-gui/src/views/settings.rs)) handles export operations. Errors like *"Backup creation failed"* (line 219) occur when the output directory lacks write permissions. **Fixes:** - Ensure the backup directory is writable (default is the current working directory) - On Windows, verify the path contains no prohibited characters - Change the backup location via the *Backup folder* setting or run with elevated privileges **Configuration parsing errors** in [`crates/uad-core/src/config.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/config.rs) manifest as *"Failed to read config file"*. Validate the TOML syntax in `~/.config/uad/config.toml` using a linter, or delete the file to regenerate defaults. ## Code Examples for Common Recovery Scenarios ### Verify ADB connectivity with verbose logging ```bash RUST_LOG=debug uad devices ``` ### Handle Samsung Knox restrictions using dry-run ```bash # Test first uad uninstall com.samsung.scloud --dry-run # If restricted, disable instead uad disable com.samsung.scloud ``` ### Target specific Android users ```bash # List packages for work profile (user 10) uad list --user 10 # Remove from specific user only uad uninstall com.example.app --user 10 ``` ### Resolve cross-user restoration ```bash # Apply to all users to prevent restoration uad uninstall com.example.app --user all ``` ### Force self-update with debugging ```bash RUST_LOG=debug uad self-update ``` ### Export package selection ```bash uad export --output ~/backups/uad_backup.json ``` ## Summary - **ADB connectivity** issues trace to `get_device_model` in [`sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/sync.rs) and require PATH verification and USB debugging enablement - **Permission errors** are decoded by `make_friendly_error_message` and often require switching from uninstall to disable on restricted devices like Samsung Knox - **Cross-user behavior** detection in [`sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/sync.rs) reveals when packages restore across Android profiles; use `--user all` to synchronize removals - **Self-update failures** in [`update.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/update.rs) typically indicate network or GitHub API rate limiting; manual compilation from source is the reliable fallback - **Configuration and backup** errors stem from file permissions or invalid TOML syntax in the config directory ## Frequently Asked Questions ### Why does UAD-NG show "no devices found" when ADB works fine in my terminal? UAD-NG launches its own ADB process and requires the `adb` binary to be in your system PATH, not just your user shell profile. Verify with `adb version` in a fresh terminal window, then restart the UAD-NG GUI or CLI. If the issue persists, restart the ADB server with `adb kill-server && adb start-server` to clear stale daemon connections. ### Can I debloat Samsung devices without triggering Knox security warnings? Samsung Knox triggers `DELETE_FAILED_USER_RESTRICTED` errors in [`sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/sync.rs) when attempting to uninstall protected packages. According to the source code analysis, you should use the **disable** command instead of uninstall for Knox-protected apps, or temporarily disable the Knox security profile in your device settings before running UAD-NG operations. ### What causes the "cross-user restoration" notification and how do I fix it? Android maintains package states per user profile (work profiles, secondary users). When you uninstall an app from user 0 but it remains enabled on user 10, `detect_cross_user_behavior` in [`sync.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/sync.rs) detects this mismatch. Use the `--user all` flag in the CLI or enable *Apply to all users* in the GUI to ensure the package is removed or disabled across every profile simultaneously. ### How do I troubleshoot "Failed to check update" errors in the GUI? This error originates in [`crates/uad-core/src/update.rs`](https://github.com/Universal-Debloater-Alliance/universal-android-debloater-next-generation/blob/main/crates/uad-core/src/update.rs) when the GitHub API request fails or returns a rate-limiting 403 response. Check your internet connection and verify you can reach `https://api.github.com`. If you encounter rate limiting, wait one hour before retrying, or manually build the latest version from source using `cargo build --release -p uad-cli`.