diff --git a/launcher/src/app/auth_state.rs b/launcher/src/app/auth_state.rs
index cc6bc73..2fb3031 100644
--- a/launcher/src/app/auth_state.rs
+++ b/launcher/src/app/auth_state.rs
@@ -227,7 +227,7 @@ impl AuthState {
     }
 
     pub fn reset_auth_if_needed(&mut self, new_auth_data: &AuthData) {
-        if self.runtime_auth.contains_key(&new_auth_data.get_id()) {
+        if !self.runtime_auth.contains_key(&new_auth_data.get_id()) {
             self.auth_status = AuthStatus::NotAuthorized;
             self.auth_task = None;
         }
diff --git a/launcher/src/config/runtime_config.rs b/launcher/src/config/runtime_config.rs
index eebd198..10eed29 100644
--- a/launcher/src/config/runtime_config.rs
+++ b/launcher/src/config/runtime_config.rs
@@ -1,7 +1,11 @@
+use env_logger::Builder;
+use log::LevelFilter;
 use serde::{Deserialize, Serialize};
-use shared::version::extra_version_metadata::AuthData;
-use std::collections::HashMap;
+use shared::{paths::get_logs_dir, version::extra_version_metadata::AuthData};
+use std::io::Write;
 use std::path::PathBuf;
+use std::sync::Mutex;
+use std::{collections::HashMap, fs::OpenOptions};
 
 use super::build_config;
 use crate::{auth::base::UserInfo, constants, lang::Lang};
@@ -44,11 +48,52 @@ pub fn get_launcher_dir(config: &Config) -> PathBuf {
     data_dir
 }
 
-fn get_config_path() -> PathBuf {
-    let data_dir = dirs::data_dir().expect("Failed to get data directory");
+fn get_data_dir() -> PathBuf {
+    let data_dir = dirs::data_dir()
+        .expect("Failed to get data directory")
+        .join(build_config::get_data_launcher_name());
+    if !data_dir.exists() {
+        std::fs::create_dir_all(&data_dir).expect("Failed to create data directory");
+    }
     data_dir
-        .join(build_config::get_data_launcher_name())
-        .join("config.json")
+}
+
+const CONFIG_FILENAME: &str = "config.json";
+
+fn get_config_path() -> PathBuf {
+    get_data_dir().join(CONFIG_FILENAME)
+}
+
+const LOGS_FILENAME: &str = "launcher.log";
+
+fn get_logs_path() -> PathBuf {
+    let logs_dir = get_logs_dir(&get_data_dir());
+    if !logs_dir.exists() {
+        std::fs::create_dir_all(&logs_dir).expect("Failed to create logs directory");
+    }
+    logs_dir.join(LOGS_FILENAME)
+}
+
+pub fn setup_logger() {
+    let log_file = OpenOptions::new()
+        .create(true)
+        .write(true)
+        .append(true)
+        .open(get_logs_path())
+        .unwrap();
+
+    let log_file = Mutex::new(log_file);
+
+    let mut builder = Builder::new();
+    builder.filter(None, LevelFilter::Info);
+
+    builder.format(move |buf, record| {
+        let mut log_file = log_file.lock().unwrap();
+        writeln!(log_file, "{} - {}", record.level(), record.args()).unwrap();
+        writeln!(buf, "{} - {}", record.level(), record.args())
+    });
+
+    builder.init();
 }
 
 pub fn get_assets_dir(config: &Config) -> PathBuf {
diff --git a/launcher/src/main.rs b/launcher/src/main.rs
index e640294..4af1b5b 100644
--- a/launcher/src/main.rs
+++ b/launcher/src/main.rs
@@ -11,16 +11,14 @@ mod update_app;
 mod utils;
 mod version;
 
-use config::runtime_config;
+use config::runtime_config::{self, setup_logger};
+use utils::set_sigint_handler;
 
 fn main() {
-    env_logger::init();
-
-    utils::set_sigint_handler();
+    set_sigint_handler();
+    setup_logger();
 
     let config = runtime_config::load_config();
-
     update_app::app::run_gui(&config);
-
     app::app::run_gui(config);
 }
diff --git a/launcher/src/version/merged_version_metadata.rs b/launcher/src/version/merged_version_metadata.rs
index 01f9929..366b3df 100644
--- a/launcher/src/version/merged_version_metadata.rs
+++ b/launcher/src/version/merged_version_metadata.rs
@@ -66,9 +66,10 @@ fn merge_two_metadata(
         parent_metadata.arguments.game = arguments.game;
     }
 
-    let parent_id = parent_metadata.id.clone();
-    parent_metadata.hierarchy_ids.push(parent_id);
-    parent_metadata.id = child_metadata.id.clone();
+    parent_metadata
+        .hierarchy_ids
+        .push(child_metadata.id.clone());
+    parent_metadata.id = child_metadata.id;
 
     if let Some(java_version) = child_metadata.java_version {
         parent_metadata.java_version = java_version;
diff --git a/launcher/src/version/sync.rs b/launcher/src/version/sync.rs
index 902013a..cdf60da 100644
--- a/launcher/src/version/sync.rs
+++ b/launcher/src/version/sync.rs
@@ -275,10 +275,16 @@ pub async fn sync_modpack(
             .get_check_downloads(&assets_dir, version_metadata.get_resources_url_base())?,
     );
 
+    info!(
+        "Got {} check download entries",
+        check_download_entries.len()
+    );
     progress_bar.set_message(LangMessage::CheckingFiles);
     let download_entries =
         files::get_download_entries(check_download_entries, progress_bar.clone()).await?;
 
+    info!("Got {} download entries", download_entries.len());
+
     let libraries_changed = download_entries
         .iter()
         .any(|entry| entry.path.starts_with(&libraries_dir));