diff --git a/src/cli/debug.rs b/src/cli/debug.rs
index c9c7f4e..b8834e1 100644
--- a/src/cli/debug.rs
+++ b/src/cli/debug.rs
@@ -1,13 +1,13 @@
 use crate::config::AppConfig;
 use crate::cpu;
 use crate::monitor;
-use std::error::Error;
+use crate::util::error::AppError;
 use std::fs;
 use std::process::{Command, Stdio};
 use std::time::Duration;
 
 /// Prints comprehensive debug information about the system
-pub fn run_debug(config: &AppConfig) -> Result<(), Box<dyn Error>> {
+pub fn run_debug(config: &AppConfig) -> Result<(), AppError> {
     println!("=== SUPERFREQ DEBUG INFORMATION ===");
     println!("Version: {}", env!("CARGO_PKG_VERSION"));
 
@@ -201,26 +201,31 @@ pub fn run_debug(config: &AppConfig) -> Result<(), Box<dyn Error>> {
 
             Ok(())
         }
-        Err(e) => Err(Box::new(e) as Box<dyn Error>),
+        Err(e) => Err(AppError::Monitor(e)),
     }
 }
 
 /// Get kernel version information
-fn get_kernel_info() -> Result<String, Box<dyn Error>> {
-    let output = Command::new("uname").arg("-r").output()?;
+fn get_kernel_info() -> Result<String, AppError> {
+    let output = Command::new("uname")
+        .arg("-r")
+        .output()
+        .map_err(AppError::Io)?;
 
-    let kernel_version = String::from_utf8(output.stdout)?;
+    let kernel_version = String::from_utf8(output.stdout)
+        .map_err(|e| AppError::Generic(format!("Failed to parse kernel version: {e}")))?;
     Ok(kernel_version.trim().to_string())
 }
 
 /// Get system uptime
-fn get_system_uptime() -> Result<Duration, Box<dyn Error>> {
-    let uptime_str = fs::read_to_string("/proc/uptime")?;
+fn get_system_uptime() -> Result<Duration, AppError> {
+    let uptime_str = fs::read_to_string("/proc/uptime").map_err(AppError::Io)?;
     let uptime_secs = uptime_str
         .split_whitespace()
         .next()
-        .ok_or("Invalid uptime format")?
-        .parse::<f64>()?;
+        .ok_or_else(|| AppError::Generic("Invalid uptime format".to_string()))?
+        .parse::<f64>()
+        .map_err(|e| AppError::Generic(format!("Failed to parse uptime: {e}")))?;
 
     Ok(Duration::from_secs_f64(uptime_secs))
 }
@@ -237,14 +242,16 @@ fn check_and_print_sysfs_path(path: &str, description: &str) {
 }
 
 /// Check if a systemd service is active
-fn is_systemd_service_active(service_name: &str) -> Result<bool, Box<dyn Error>> {
+fn is_systemd_service_active(service_name: &str) -> Result<bool, AppError> {
     let output = Command::new("systemctl")
         .arg("is-active")
         .arg(format!("{service_name}.service"))
         .stdout(Stdio::piped()) // capture stdout instead of letting it print
         .stderr(Stdio::null()) // redirect stderr to null
-        .output()?;
+        .output()
+        .map_err(AppError::Io)?;
 
-    let status = String::from_utf8(output.stdout)?;
+    let status = String::from_utf8(output.stdout)
+        .map_err(|e| AppError::Generic(format!("Failed to parse systemctl output: {e}")))?;
     Ok(status.trim() == "active")
 }
diff --git a/src/daemon.rs b/src/daemon.rs
index 82349cb..9881110 100644
--- a/src/daemon.rs
+++ b/src/daemon.rs
@@ -3,6 +3,7 @@ use crate::config::{AppConfig, LogLevel};
 use crate::core::SystemReport;
 use crate::engine;
 use crate::monitor;
+use crate::util::error::AppError;
 use log::{LevelFilter, debug, error, info, warn};
 use std::collections::VecDeque;
 use std::fs::File;
@@ -342,7 +343,7 @@ impl SystemHistory {
 }
 
 /// Run the daemon
-pub fn run_daemon(mut config: AppConfig, verbose: bool) -> Result<(), Box<dyn std::error::Error>> {
+pub fn run_daemon(mut config: AppConfig, verbose: bool) -> Result<(), AppError> {
     // Set effective log level based on config and verbose flag
     let effective_log_level = if verbose {
         LogLevel::Debug
@@ -372,7 +373,7 @@ pub fn run_daemon(mut config: AppConfig, verbose: bool) -> Result<(), Box<dyn st
         info!("Received shutdown signal, exiting...");
         r.store(false, Ordering::SeqCst);
     })
-    .expect("Error setting Ctrl-C handler");
+    .map_err(|e| AppError::Generic(format!("Error setting Ctrl-C handler: {e}")))?;
 
     info!(
         "Daemon initialized with poll interval: {}s",
diff --git a/src/main.rs b/src/main.rs
index 133af98..021b285 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -10,10 +10,11 @@ mod util;
 
 use crate::config::AppConfig;
 use crate::core::{GovernorOverrideMode, TurboSetting};
-use crate::util::error::ControlError;
+use crate::util::error::{AppError, ControlError};
 use clap::{Parser, value_parser};
 use env_logger::Builder;
 use log::{debug, error, info};
+use std::error::Error;
 use std::sync::Once;
 
 #[derive(Parser, Debug)]
@@ -88,7 +89,7 @@ enum Commands {
     },
 }
 
-fn main() {
+fn main() -> Result<(), AppError> {
     // Initialize logger once for the entire application
     init_logger();
 
@@ -105,7 +106,7 @@ fn main() {
         }
     };
 
-    let command_result = match cli.command {
+    let command_result: Result<(), AppError> = match cli.command {
         // TODO: This will be moved to a different module in the future.
         Some(Commands::Info) => match monitor::collect_system_report(&config) {
             Ok(report) => {
@@ -341,41 +342,30 @@ fn main() {
                 );
                 Ok(())
             }
-            Err(e) => Err(Box::new(e) as Box<dyn std::error::Error>),
+            Err(e) => Err(AppError::Monitor(e)),
         },
-        Some(Commands::SetGovernor { governor, core_id }) => cpu::set_governor(&governor, core_id)
-            .map_err(|e| Box::new(e) as Box<dyn std::error::Error>),
+        Some(Commands::SetGovernor { governor, core_id }) => {
+            cpu::set_governor(&governor, core_id).map_err(AppError::Control)
+        }
         Some(Commands::ForceGovernor { mode }) => {
-            cpu::force_governor(mode).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
-        }
-        Some(Commands::SetTurbo { setting }) => {
-            cpu::set_turbo(setting).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+            cpu::force_governor(mode).map_err(AppError::Control)
         }
+        Some(Commands::SetTurbo { setting }) => cpu::set_turbo(setting).map_err(AppError::Control),
         Some(Commands::SetEpp { epp, core_id }) => {
-            cpu::set_epp(&epp, core_id).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+            cpu::set_epp(&epp, core_id).map_err(AppError::Control)
         }
         Some(Commands::SetEpb { epb, core_id }) => {
-            cpu::set_epb(&epb, core_id).map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+            cpu::set_epb(&epb, core_id).map_err(AppError::Control)
         }
         Some(Commands::SetMinFreq { freq_mhz, core_id }) => {
             // Basic validation for reasonable CPU frequency values
-            if let Err(e) = validate_freq(freq_mhz, "Minimum") {
-                error!("{e}");
-                Err(e)
-            } else {
-                cpu::set_min_frequency(freq_mhz, core_id)
-                    .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
-            }
+            validate_freq(freq_mhz, "Minimum")?;
+            cpu::set_min_frequency(freq_mhz, core_id).map_err(AppError::Control)
         }
         Some(Commands::SetMaxFreq { freq_mhz, core_id }) => {
             // Basic validation for reasonable CPU frequency values
-            if let Err(e) = validate_freq(freq_mhz, "Maximum") {
-                error!("{e}");
-                Err(e)
-            } else {
-                cpu::set_max_frequency(freq_mhz, core_id)
-                    .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
-            }
+            validate_freq(freq_mhz, "Maximum")?;
+            cpu::set_max_frequency(freq_mhz, core_id).map_err(AppError::Control)
         }
         Some(Commands::SetPlatformProfile { profile }) => {
             // Get available platform profiles and validate early if possible
@@ -383,26 +373,24 @@ fn main() {
                 Ok(available_profiles) => {
                     if available_profiles.contains(&profile) {
                         info!("Setting platform profile to '{profile}'");
-                        cpu::set_platform_profile(&profile)
-                            .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+                        cpu::set_platform_profile(&profile).map_err(AppError::Control)
                     } else {
                         error!(
                             "Invalid platform profile: '{}'. Available profiles: {}",
                             profile,
                             available_profiles.join(", ")
                         );
-                        Err(Box::new(ControlError::InvalidProfile(format!(
+                        Err(ControlError::InvalidProfile(format!(
                             "Invalid platform profile: '{}'. Available profiles: {}",
                             profile,
                             available_profiles.join(", ")
-                        ))) as Box<dyn std::error::Error>)
+                        ))
+                        .into())
                     }
                 }
-                Err(_) => {
+                Err(_e) => {
                     // If we can't get profiles (e.g., feature not supported), pass through to the function
-                    // which will provide appropriate error
-                    cpu::set_platform_profile(&profile)
-                        .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+                    cpu::set_platform_profile(&profile).map_err(AppError::Control)
                 }
             }
         }
@@ -415,15 +403,15 @@ fn main() {
                 error!(
                     "Start threshold ({start_threshold}) must be less than stop threshold ({stop_threshold})"
                 );
-                Err(Box::new(ControlError::InvalidValueError(format!(
+                Err(ControlError::InvalidValueError(format!(
                     "Start threshold ({start_threshold}) must be less than stop threshold ({stop_threshold})"
-                ))) as Box<dyn std::error::Error>)
+                )).into())
             } else {
                 info!(
                     "Setting battery thresholds: start at {start_threshold}%, stop at {stop_threshold}%"
                 );
                 battery::set_battery_charge_thresholds(start_threshold, stop_threshold)
-                    .map_err(|e| Box::new(e) as Box<dyn std::error::Error>)
+                    .map_err(AppError::Control)
             }
         }
         Some(Commands::Daemon { verbose }) => daemon::run_daemon(config, verbose),
@@ -440,11 +428,9 @@ fn main() {
         if let Some(source) = e.source() {
             error!("Caused by: {source}");
         }
-        // TODO: Consider specific error handling for PermissionDenied from the cpu module here.
-        // For example, check if `e.downcast_ref::<cpu::ControlError>()` matches `PermissionDenied`
-        // and print a more specific message like "Try running with sudo."
-        // We'll revisit this in the future once CPU logic is more stable.
-        if let Some(control_error) = e.downcast_ref::<ControlError>() {
+
+        // Check for permission denied errors
+        if let AppError::Control(control_error) = &e {
             if matches!(control_error, ControlError::PermissionDenied(_)) {
                 error!(
                     "Hint: This operation may require administrator privileges (e.g., run with sudo)."
@@ -454,6 +440,8 @@ fn main() {
 
         std::process::exit(1);
     }
+
+    Ok(())
 }
 
 /// Initialize the logger for the entire application
@@ -474,18 +462,17 @@ fn init_logger() {
 }
 
 /// Validate CPU frequency input values
-fn validate_freq(freq_mhz: u32, label: &str) -> Result<(), Box<dyn std::error::Error>> {
+fn validate_freq(freq_mhz: u32, label: &str) -> Result<(), AppError> {
     if freq_mhz == 0 {
         error!("{label} frequency cannot be zero");
-        Err(Box::new(ControlError::InvalidValueError(format!(
-            "{label} frequency cannot be zero"
-        ))) as Box<dyn std::error::Error>)
+        Err(ControlError::InvalidValueError(format!("{label} frequency cannot be zero")).into())
     } else if freq_mhz > 10000 {
         // Extremely high value unlikely to be valid
         error!("{label} frequency ({freq_mhz} MHz) is unreasonably high");
-        Err(Box::new(ControlError::InvalidValueError(format!(
+        Err(ControlError::InvalidValueError(format!(
             "{label} frequency ({freq_mhz} MHz) is unreasonably high"
-        ))) as Box<dyn std::error::Error>)
+        ))
+        .into())
     } else {
         Ok(())
     }
diff --git a/src/util/error.rs b/src/util/error.rs
index b52480b..8724d62 100644
--- a/src/util/error.rs
+++ b/src/util/error.rs
@@ -113,3 +113,82 @@ impl std::error::Error for EngineError {
         }
     }
 }
+
+// A unified error type for the entire application
+#[derive(Debug)]
+pub enum AppError {
+    Control(ControlError),
+    Monitor(SysMonitorError),
+    Engine(EngineError),
+    Config(crate::config::ConfigError),
+    Generic(String),
+    Io(io::Error),
+}
+
+impl From<ControlError> for AppError {
+    fn from(err: ControlError) -> Self {
+        Self::Control(err)
+    }
+}
+
+impl From<SysMonitorError> for AppError {
+    fn from(err: SysMonitorError) -> Self {
+        Self::Monitor(err)
+    }
+}
+
+impl From<EngineError> for AppError {
+    fn from(err: EngineError) -> Self {
+        Self::Engine(err)
+    }
+}
+
+impl From<crate::config::ConfigError> for AppError {
+    fn from(err: crate::config::ConfigError) -> Self {
+        Self::Config(err)
+    }
+}
+
+impl From<io::Error> for AppError {
+    fn from(err: io::Error) -> Self {
+        Self::Io(err)
+    }
+}
+
+impl From<String> for AppError {
+    fn from(err: String) -> Self {
+        Self::Generic(err)
+    }
+}
+
+impl From<&str> for AppError {
+    fn from(err: &str) -> Self {
+        Self::Generic(err.to_string())
+    }
+}
+
+impl std::fmt::Display for AppError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Self::Control(e) => write!(f, "{e}"),
+            Self::Monitor(e) => write!(f, "{e}"),
+            Self::Engine(e) => write!(f, "{e}"),
+            Self::Config(e) => write!(f, "{e}"),
+            Self::Generic(s) => write!(f, "{s}"),
+            Self::Io(e) => write!(f, "I/O error: {e}"),
+        }
+    }
+}
+
+impl std::error::Error for AppError {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        match self {
+            Self::Control(e) => Some(e),
+            Self::Monitor(e) => Some(e),
+            Self::Engine(e) => Some(e),
+            Self::Config(e) => Some(e),
+            Self::Generic(_) => None,
+            Self::Io(e) => Some(e),
+        }
+    }
+}