diff --git a/powerdnsadmin/__init__.py b/powerdnsadmin/__init__.py
index f4f5540..3f7c17a 100755
--- a/powerdnsadmin/__init__.py
+++ b/powerdnsadmin/__init__.py
@@ -49,7 +49,7 @@ def create_app(config=None):
     # HSTS
     if app.config.get('HSTS_ENABLED'):
         from flask_sslify import SSLify
-        _sslify = SSLify(app)
+        _sslify = SSLify(app) # lgtm [py/unused-import]
 
     # Load app's components
     assets.init_app(app)
diff --git a/powerdnsadmin/decorators.py b/powerdnsadmin/decorators.py
index e06deff..1486928 100644
--- a/powerdnsadmin/decorators.py
+++ b/powerdnsadmin/decorators.py
@@ -1,7 +1,7 @@
 import base64
 import binascii
 from functools import wraps
-from flask import g, redirect, url_for, request, abort, current_app, render_template
+from flask import g, request, abort, current_app, render_template
 from flask_login import current_user
 
 from .models import User, ApiKey, Setting, Domain
diff --git a/powerdnsadmin/lib/utils.py b/powerdnsadmin/lib/utils.py
index e690b6b..821489f 100644
--- a/powerdnsadmin/lib/utils.py
+++ b/powerdnsadmin/lib/utils.py
@@ -9,7 +9,6 @@ import os
 from distutils.version import StrictVersion
 from urllib.parse import urlparse
 from datetime import datetime, timedelta
-from threading import Thread
 
 from .certutil import KEY_FILE, CERT_FILE
 
@@ -58,12 +57,18 @@ def fetch_remote(remote_url,
             r.raise_for_status()
     except Exception as e:
         msg = "Returned status {0} and content {1}"
-        raise RuntimeError('Error while fetching {0}'.format(remote_url))
+        raise RuntimeError('Error while fetching {0}. {1}'.format(
+            remote_url, msg))
 
     return r
 
 
-def fetch_json(remote_url, method='GET', data=None, params=None, headers=None, timeout=None):
+def fetch_json(remote_url,
+               method='GET',
+               data=None,
+               params=None,
+               headers=None,
+               timeout=None):
     r = fetch_remote(remote_url,
                      method=method,
                      data=data,
@@ -78,7 +83,10 @@ def fetch_json(remote_url, method='GET', data=None, params=None, headers=None, t
     if r.status_code == 204:
         return {}
     elif r.status_code == 409:
-        return {'error': 'Resource already exists or conflict', 'http_code': r.status_code}
+        return {
+            'error': 'Resource already exists or conflict',
+            'http_code': r.status_code
+        }
 
     try:
         assert ('json' in r.headers['content-type'])
diff --git a/powerdnsadmin/models/__init__.py b/powerdnsadmin/models/__init__.py
index 62eccc3..714a198 100644
--- a/powerdnsadmin/models/__init__.py
+++ b/powerdnsadmin/models/__init__.py
@@ -20,4 +20,4 @@ from .record_entry import RecordEntry
 
 def init_app(app):
     db.init_app(app)
-    _migrate = Migrate(app, db)
+    _migrate = Migrate(app, db)  # lgtm [py/unused-import]
diff --git a/powerdnsadmin/models/domain.py b/powerdnsadmin/models/domain.py
index 5929090..31a2cbe 100644
--- a/powerdnsadmin/models/domain.py
+++ b/powerdnsadmin/models/domain.py
@@ -287,7 +287,8 @@ class Domain(db.Model):
             account_id = None
         # add new domain
         d = Domain()
-        d.name = domain['name'].rstrip('.')
+        d.name = domain['name'].rstrip(
+            '.')  # lgtm [py/modification-of-default-value]
         d.master = str(domain['masters'])
         d.type = domain['kind']
         d.serial = domain['serial']
diff --git a/powerdnsadmin/models/server.py b/powerdnsadmin/models/server.py
index 7e32d33..1c1deba 100644
--- a/powerdnsadmin/models/server.py
+++ b/powerdnsadmin/models/server.py
@@ -3,7 +3,6 @@ from flask import current_app
 from urllib.parse import urljoin
 
 from ..lib import utils
-from .base import db
 from .setting import Setting
 
 
diff --git a/powerdnsadmin/models/setting.py b/powerdnsadmin/models/setting.py
index ee89a14..6f44663 100644
--- a/powerdnsadmin/models/setting.py
+++ b/powerdnsadmin/models/setting.py
@@ -2,7 +2,6 @@ import sys
 import pytimeparse
 from ast import literal_eval
 from distutils.util import strtobool
-from distutils.version import StrictVersion
 
 from .base import db
 
diff --git a/powerdnsadmin/routes/admin.py b/powerdnsadmin/routes/admin.py
index 85c217f..f23b93a 100644
--- a/powerdnsadmin/routes/admin.py
+++ b/powerdnsadmin/routes/admin.py
@@ -1,15 +1,13 @@
 import re
 import json
 import traceback
-import datetime
 from ast import literal_eval
 from distutils.version import StrictVersion
-from flask import Blueprint, render_template, make_response, url_for, current_app, g, session, request, redirect, jsonify, abort
-from flask_login import login_user, login_required, current_user
+from flask import Blueprint, render_template, make_response, url_for, current_app, request, redirect, jsonify, abort
+from flask_login import login_required, current_user
 
-from .base import login_manager
 from ..decorators import operator_role_required, admin_role_required
-from ..models.user import User, Anonymous
+from ..models.user import User
 from ..models.account import Account
 from ..models.account_user import AccountUser
 from ..models.role import Role
diff --git a/powerdnsadmin/routes/base.py b/powerdnsadmin/routes/base.py
index d1df359..8e365bf 100644
--- a/powerdnsadmin/routes/base.py
+++ b/powerdnsadmin/routes/base.py
@@ -1,6 +1,6 @@
 import base64
 from flask import render_template, url_for, redirect, session, request, current_app
-from flask_login import LoginManager, login_user
+from flask_login import LoginManager
 
 from ..models.user import User
 
diff --git a/powerdnsadmin/routes/dashboard.py b/powerdnsadmin/routes/dashboard.py
index b062b92..877b07e 100644
--- a/powerdnsadmin/routes/dashboard.py
+++ b/powerdnsadmin/routes/dashboard.py
@@ -1,6 +1,6 @@
-from flask import Blueprint, render_template, make_response, url_for, current_app, request, jsonify, redirect
+from flask import Blueprint, render_template, url_for, current_app, request, jsonify, redirect
 from flask_login import login_required, current_user
-from sqlalchemy import not_, or_
+from sqlalchemy import not_
 
 from ..lib.utils import customBoxes
 from ..models.user import User
@@ -33,7 +33,7 @@ def domains_custom(boxId):
             .outerjoin(Account, Domain.account_id == Account.id) \
             .outerjoin(AccountUser, Account.id == AccountUser.account_id) \
             .filter(
-                db.or_(
+                d(
                     DomainUser.user_id == current_user.id,
                     AccountUser.user_id == current_user.id
                 ))
diff --git a/powerdnsadmin/routes/domain.py b/powerdnsadmin/routes/domain.py
index e920738..67ed4cc 100644
--- a/powerdnsadmin/routes/domain.py
+++ b/powerdnsadmin/routes/domain.py
@@ -1,14 +1,12 @@
 import re
 import json
 import traceback
-import datetime
 from distutils.version import StrictVersion
-from flask import Blueprint, render_template, make_response, url_for, current_app, g, session, request, redirect, abort, jsonify
-from flask_login import login_user, login_required, current_user
+from flask import Blueprint, render_template, make_response, url_for, current_app, request, redirect, abort, jsonify
+from flask_login import login_required, current_user
 
-from .base import login_manager
 from ..decorators import can_create_domain, operator_role_required, can_access_domain, can_configure_dnssec
-from ..models.user import User, Anonymous
+from ..models.user import User
 from ..models.account import Account
 from ..models.setting import Setting
 from ..models.history import History
diff --git a/powerdnsadmin/routes/user.py b/powerdnsadmin/routes/user.py
index 6d3d060..4995aad 100644
--- a/powerdnsadmin/routes/user.py
+++ b/powerdnsadmin/routes/user.py
@@ -1,12 +1,10 @@
 import qrcode as qrc
 import qrcode.image.svg as qrc_svg
 from io import BytesIO
-from flask import Blueprint, request, render_template, make_response, jsonify, redirect, url_for, current_app, session, g
-from flask_login import current_user, login_user, logout_user, login_required
+from flask import Blueprint, request, render_template, make_response, jsonify, redirect, url_for, session
+from flask_login import current_user, login_required
 
-from .base import login_manager
 from ..models.user import User
-from ..models.role import Role
 
 user_bp = Blueprint('user',
                     __name__,
diff --git a/update_zones.py b/update_zones.py
index 6e2f449..f13b873 100644
--- a/update_zones.py
+++ b/update_zones.py
@@ -13,7 +13,6 @@
 import sys
 import logging
 
-from flask import current_app
 from powerdnsadmin import create_app
 from powerdnsadmin.models.domain import Domain
 from powerdnsadmin.models.setting import Setting