diff --git a/server/src/Group.cpp b/server/src/Group.cpp
index 7815d82..771b7f1 100644
--- a/server/src/Group.cpp
+++ b/server/src/Group.cpp
@@ -92,6 +92,7 @@ GroupManager::GroupManager(const shared_ptr<VirtualServer> &server, sql::SqlMana
 GroupManager::~GroupManager() {}
 
 bool GroupManager::loadGroupFormDatabase(GroupId id) {
+    std::lock_guard glock{this->group_lock};
     if(id == 0){
         this->groups.clear();
 
@@ -115,8 +116,13 @@ bool GroupManager::loadGroupFormDatabase(GroupId id) {
 
 std::vector<std::shared_ptr<Group>> GroupManager::availableGroups(bool root) {
     std::vector<std::shared_ptr<Group>> response;
-    for(const auto& group : this->groups)
-        response.push_back(group);
+
+    {
+        std::lock_guard glock{this->group_lock};
+        for(const auto& group : this->groups)
+            response.push_back(group);
+    }
+
     if(root && this->root){
         auto elm = this->root->availableGroups();
         for(const auto& e : elm)
@@ -127,9 +133,14 @@ std::vector<std::shared_ptr<Group>> GroupManager::availableGroups(bool root) {
 
 std::vector<std::shared_ptr<Group>> GroupManager::availableServerGroups(bool root){
     std::vector<std::shared_ptr<Group>> response;
-    for(const auto& group : this->groups)
-        if(group->target() == GroupTarget::GROUPTARGET_SERVER)
-            response.push_back(group);
+
+    {
+        std::lock_guard glock{this->group_lock};
+        for(const auto& group : this->groups)
+            if(group->target() == GroupTarget::GROUPTARGET_SERVER)
+                response.push_back(group);
+    }
+
     if(root && this->root){
         auto elm = this->root->availableServerGroups();
         for(const auto& e : elm)
@@ -140,9 +151,12 @@ std::vector<std::shared_ptr<Group>> GroupManager::availableServerGroups(bool roo
 
 std::vector<std::shared_ptr<Group>> GroupManager::availableChannelGroups(bool root) {
     std::vector<std::shared_ptr<Group>> response;
-    for(const auto& group : this->groups)
-        if(group->target() == GroupTarget::GROUPTARGET_CHANNEL)
-            response.push_back(group);
+    {
+        std::lock_guard glock{this->group_lock};
+        for(const auto& group : this->groups)
+            if(group->target() == GroupTarget::GROUPTARGET_CHANNEL)
+                response.push_back(group);
+    }
     if(root && this->root){
         auto elm = this->root->availableChannelGroups(true);
         for(const auto& e : elm)
@@ -237,6 +251,7 @@ void GroupManager::handleChannelDeleted(const ChannelId& channel_id) {
 }
 
 bool GroupManager::isLocalGroup(std::shared_ptr<Group> gr) {
+    std::lock_guard glock{this->group_lock};
     return std::find(this->groups.begin(), this->groups.end(), gr) != this->groups.end();
 }
 
@@ -252,9 +267,12 @@ std::shared_ptr<Group> GroupManager::defaultGroup(GroupTarget type, bool enforce
     auto group = this->findGroupLocal(id);
     if(group || enforce_property) return group;
 
-    for(auto elm : this->groups)
-        if(elm->target() == type)
-            return elm;
+    {
+        std::lock_guard glock{this->group_lock};
+        for(auto elm : this->groups)
+            if(elm->target() == type)
+                return elm;
+    }
 
     return nullptr; //Worst case!
 }
@@ -266,6 +284,7 @@ std::shared_ptr<Group> GroupManager::findGroup(GroupId groupId) {
 }
 
 std::shared_ptr<Group> GroupManager::findGroupLocal(GroupId groupId) {
+    std::lock_guard glock{this->group_lock};
     for(const auto& elm : this->groups)
         if(elm->groupId() == groupId) return elm;
     return nullptr;
@@ -273,8 +292,11 @@ std::shared_ptr<Group> GroupManager::findGroupLocal(GroupId groupId) {
 
 std::vector<std::shared_ptr<Group>> GroupManager::findGroup(GroupTarget target, std::string name) {
     vector<shared_ptr<Group>> res;
-    for(const auto &elm : this->groups)
-        if(elm->name() == name && elm->target() == target) res.push_back(elm);
+    {
+        std::lock_guard glock{this->group_lock};
+        for(const auto &elm : this->groups)
+            if(elm->name() == name && elm->target() == target) res.push_back(elm);
+    }
     if(this->root) {
         auto r = root->findGroup(target, name);
         for(const auto &e : r) res.push_back(e);
@@ -305,6 +327,8 @@ std::shared_ptr<Group> GroupManager::createGroup(GroupTarget target, GroupType t
     std::shared_ptr<Group> group = std::make_shared<Group>(this, target, type, groupId);
     group->properties()[property::GROUP_NAME] = name;
     group->setPermissionManager(serverInstance->databaseHelper()->loadGroupPermissions(this->server.lock(), group->groupId()));
+
+    std::lock_guard glock{this->group_lock};
     this->groups.push_back(group);
     return group;
 }
@@ -394,7 +418,10 @@ bool GroupManager::deleteGroup(std::shared_ptr<Group> group) {
         return false;
     }
 
-    this->groups.erase(std::find(this->groups.begin(), this->groups.end(), group));
+    {
+        std::lock_guard glock{this->group_lock};
+        this->groups.erase(std::find(this->groups.begin(), this->groups.end(), group));
+    }
 
     /* erase the group out of our cache */
     {
diff --git a/server/src/Group.h b/server/src/Group.h
index 4a9323d..eab8861 100644
--- a/server/src/Group.h
+++ b/server/src/Group.h
@@ -224,7 +224,10 @@ namespace ts {
             ServerId getServerId();
 
             sql::SqlManager* sql;
+
+            std::mutex group_lock{};
             std::vector<std::shared_ptr<Group>> groups;
+
             threads::Mutex cacheLock;
             std::vector<std::shared_ptr<CachedClient>> cachedClients;
 
diff --git a/server/src/VirtualServer.cpp b/server/src/VirtualServer.cpp
index 6c98452..d05edd9 100644
--- a/server/src/VirtualServer.cpp
+++ b/server/src/VirtualServer.cpp
@@ -758,9 +758,9 @@ bool VirtualServer::notifyServerEdited(std::shared_ptr<ConnectedClient> invoker,
 }
 
 bool VirtualServer::notifyClientPropertyUpdates(std::shared_ptr<ConnectedClient> client, const deque<const property::PropertyDescription*>& keys, bool selfNotify) {
-    if(keys.empty()) return false;
+    if(keys.empty() || !client) return false;
     this->forEachClient([&](const shared_ptr<ConnectedClient>& cl) {
-        shared_lock client_channel_lock(client->channel_lock);
+        shared_lock client_channel_lock(cl->channel_lock);
         if(cl->isClientVisible(client, false) || (cl == client && selfNotify))
             cl->notifyClientUpdated(client, keys, false);
     });
diff --git a/shared b/shared
index f404d5e..246e57e 160000
--- a/shared
+++ b/shared
@@ -1 +1 @@
-Subproject commit f404d5e1fa5ed1cfbe3ef9a97c0e81c1fba943ff
+Subproject commit 246e57e69d61d25d92e76c2af0368eac18536ac1