diff --git a/wo/cli/plugins/stack_pref.py b/wo/cli/plugins/stack_pref.py
index 048fe80..54a8e8e 100644
--- a/wo/cli/plugins/stack_pref.py
+++ b/wo/cli/plugins/stack_pref.py
@@ -27,7 +27,6 @@ from wo.core.variables import WOVariables
 
 def pre_pref(self, apt_packages):
     """Pre settings to do before installation packages"""
-    apt_repo_keys = []
 
     if ((["mariadb-server"] in apt_packages) or
             (["mariadb-client"] in apt_packages)):
@@ -41,8 +40,8 @@ def pre_pref(self, apt_packages):
                       'MariaDB.pref', 'w') as mysql_pref_file:
                 mysql_pref_file.write(mysql_pref)
             WORepo.add(self, repo_url=WOVariables.wo_mysql_repo)
-            apt_repo_keys = (apt_repo_keys +
-                             ['0xcbcb082a1bb943db', '0xF1656F24C74CD1D8'])
+            WORepo.add_keys(self, WOVariables.wo_mysql_keys,
+                            keyserver='hkp://keys.gnupg.net:80')
     if ["mariadb-server"] in apt_packages:
         # generate random 24 characters root password
         chars = ''.join(random.sample(string.ascii_letters, 24))
@@ -113,6 +112,7 @@ def pre_pref(self, apt_packages):
             apt_repo_keys = apt_repo_keys + WOVariables.wo_nginx_key
             WORepo.add(self, repo_url=WOVariables.wo_nginx_repo)
             Log.debug(self, 'Adding repository for Nginx')
+            WORepo.add_key(self, WOVariables.wo_nginx_key)
 
     # add php repository
     if (set(WOVariables.wo_php73).issubset(set(apt_packages)) or
@@ -133,7 +133,7 @@ def pre_pref(self, apt_packages):
             Log.debug(self, 'Adding repo_url of php for debian')
             WORepo.add(self, repo_url=WOVariables.wo_php_repo)
             Log.debug(self, 'Adding deb.sury GPG key')
-            apt_repo_keys = apt_repo_keys + WOVariables.wo_php_key
+            WORepo.add_key(self, WOVariables.wo_php_key)
     # add redis repository
     if set(['redis-server']).issubset(set(apt_packages)):
         Log.info(self, "Adding repository for Redis, please wait...")
@@ -141,9 +141,6 @@ def pre_pref(self, apt_packages):
             Log.debug(self, 'Adding ppa for redis')
             WORepo.add(self, ppa=WOVariables.wo_redis_repo)
 
-    if (apt_repo_keys):
-        WORepo.add_key(self, apt_repo_keys)
-
 
 def post_pref(self, apt_packages, packages, upgrade=False):
     """Post activity after installation of packages"""
diff --git a/wo/cli/plugins/stack_upgrade.py b/wo/cli/plugins/stack_upgrade.py
index 4f052c3..694a198 100644
--- a/wo/cli/plugins/stack_upgrade.py
+++ b/wo/cli/plugins/stack_upgrade.py
@@ -62,7 +62,6 @@ class WOStackUpgradeController(CementBaseController):
         # All package update
         apt_packages = []
         packages = []
-        nginx_packages = []
         self.msg = []
         pargs = self.app.pargs
 
diff --git a/wo/core/apt_repo.py b/wo/core/apt_repo.py
index be2e3e3..1684b6e 100644
--- a/wo/core/apt_repo.py
+++ b/wo/core/apt_repo.py
@@ -84,10 +84,15 @@ class WORepo():
         default keyserver is hkp://keyserver.ubuntu.com
         user can provide other keyserver with keyserver="hkp://xyz"
         """
-        WOShellExec.cmd_exec(self, "apt-key adv --keyserver {serv}"
-                             .format(serv=(keyserver or
-                                           "hkp://keyserver.ubuntu.com")) +
-                             " --recv-keys {key}".format(key=keyid))
+        try:
+            WOShellExec.cmd_exec(
+                self, "apt-key adv --keyserver {serv}"
+                .format(serv=(keyserver or
+                              "hkp://keyserver.ubuntu.com")) +
+                " --recv-keys {key}".format(key=keyid))
+        except Exception as e:
+            Log.debug(self, "{0}".format(e))
+            Log.error(self, "Unable to import repo key")
 
     def add_keys(self, keyids, keyserver=None):
         """
@@ -96,7 +101,12 @@ class WORepo():
         user can provide other keyserver with keyserver="hkp://xyz"
         """
         all_keys = ' '.join(keyids)
-        WOShellExec.cmd_exec(self, "apt-key adv --keyserver {serv}"
-                             .format(serv=(keyserver or
-                                           "hkp://keyserver.ubuntu.com")) +
-                             " --recv-keys {0}".format(all_keys))
+        try:
+            WOShellExec.cmd_exec(
+                self, "apt-key adv --keyserver {serv}"
+                .format(serv=(keyserver or
+                              "hkp://keyserver.ubuntu.com")) +
+                " --recv-keys {keys}".format(keys=all_keys))
+        except Exception as e:
+            Log.debug(self, "{0}".format(e))
+            Log.error(self, "Unable to import repo keys")
diff --git a/wo/core/aptget.py b/wo/core/aptget.py
index 3bff57e..e41a4f6 100644
--- a/wo/core/aptget.py
+++ b/wo/core/aptget.py
@@ -54,7 +54,7 @@ class WOAptGet():
                               "`tail /var/log/wo/wordops.log` "
                               "and please try again...")
 
-        except Exception as e:
+        except Exception:
             Log.error(self, "apt-get update exited with error")
 
     def check_upgrade(self):