diff --git a/.gitignore b/.gitignore
index 37825920..b481045f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,3 @@
 .idea
 *.iml
-.DS_Store
-*.db
 data
diff --git a/apiclient.py b/apiclient.py
index 2e28e9d2..cd772423 100644
--- a/apiclient.py
+++ b/apiclient.py
@@ -10,7 +10,10 @@ class ApiClient:
         return newclient
 
     def __call__(self, *args, **kwargs):
-        return requests.get(self.url, params=kwargs)
+        try:
+            return requests.get(self.url, params=kwargs)
+        except requests.exceptions.ConnectionError:
+            return None
 
 
 client = ApiClient('http://127.0.0.1:5000/openqq')
diff --git a/app.py b/app.py
index ebcce585..e55290cd 100644
--- a/app.py
+++ b/app.py
@@ -91,7 +91,7 @@ def _index():
     return '', 204
 
 
-def load_commands():
+def _load_commands():
     command_mod_files = filter(
         lambda filename: filename.endswith('.py') and not filename.startswith('_'),
         os.listdir(get_commands_dir())
@@ -106,5 +106,5 @@ def load_commands():
 
 
 if __name__ == '__main__':
-    load_commands()
+    _load_commands()
     app.run(host='127.0.0.1', port=8888)
diff --git a/command.py b/command.py
index 6712cd06..e429d4fe 100644
--- a/command.py
+++ b/command.py
@@ -7,15 +7,15 @@ from little_shit import SkipException, get_command_name_separators
 _command_name_seps = get_command_name_separators()
 
 
-class CommandNotExistsError(BaseException):
+class CommandNotExistsError(Exception):
     pass
 
 
-class CommandPermissionError(BaseException):
+class CommandPermissionError(Exception):
     pass
 
 
-class CommandScopeError(BaseException):
+class CommandScopeError(Exception):
     def __init__(self, msg_type):
         self.msg_type = msg_type
 
diff --git a/little_shit.py b/little_shit.py
index fb537f5b..9a956a1f 100644
--- a/little_shit.py
+++ b/little_shit.py
@@ -3,7 +3,7 @@ import os
 from config import config
 
 
-class SkipException(BaseException):
+class SkipException(Exception):
     pass
 
 
@@ -25,7 +25,7 @@ def get_db_dir():
 
 
 def get_default_db_path():
-    return os.path.join(get_db_dir(), 'default.db')
+    return os.path.join(get_db_dir(), 'default.sqlite')
 
 
 def get_tmp_dir():
diff --git a/requirements.txt b/requirements.txt
index 5576ba5d..bbe71122 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,3 +1,4 @@
+apscheduler
 requests
 cachetools
 pytz