diff --git a/packages/stream_chat/lib/src/api/channel.dart b/packages/stream_chat/lib/src/api/channel.dart
index c4bcef33..4ed2c939 100644
--- a/packages/stream_chat/lib/src/api/channel.dart
+++ b/packages/stream_chat/lib/src/api/channel.dart
@@ -985,7 +985,7 @@ class Channel {
     if (preferOffline && cid != null) {
       final updatedState =
           (await _client.chatPersistenceClient?.getChannelStateByCid(
-        cid,
+        cid!,
         messagePagination: messagesPagination,
       ))!;
       if (updatedState.messages.isNotEmpty) {
@@ -1014,7 +1014,7 @@ class Channel {
         rethrow;
       }
       return _client.chatPersistenceClient!.getChannelStateByCid(
-        cid,
+        cid!,
         messagePagination: messagesPagination,
       );
     }
@@ -1122,7 +1122,10 @@ class Channel {
 
     if (clearHistory == true) {
       state!.truncate();
-      await _client.chatPersistenceClient?.deleteMessageByCid(_cid);
+      final cid = _cid;
+      if (cid != null) {
+        await _client.chatPersistenceClient?.deleteMessageByCid(cid);
+      }
     }
 
     return _client.decode(response.data, EmptyResponse.fromJson);
@@ -1252,12 +1255,12 @@ class ChannelClientState {
     _startCleaningPinnedMessages();
 
     _channel._client.chatPersistenceClient
-        ?.getChannelThreads(_channel.cid)
+        ?.getChannelThreads(_channel.cid!)
         .then((threads) {
       _threads = threads;
     }).then((_) {
       _channel._client.chatPersistenceClient
-          ?.getChannelStateByCid(_channel.cid)
+          ?.getChannelStateByCid(_channel.cid!)
           .then((state) {
         // Replacing the persistence state members with the latest
         // `channelState.members` as they may have changes over the time.
@@ -1734,7 +1737,7 @@ class ChannelClientState {
 
   set _threads(Map<String?, List<Message>?> v) {
     _channel._client.chatPersistenceClient?.updateMessages(
-      _channel.cid,
+      _channel.cid!,
       v.values.expand((v) => v!).toList(),
     );
     _threadsController.add(v);
diff --git a/packages/stream_chat/lib/src/client.dart b/packages/stream_chat/lib/src/client.dart
index 1066c670..69b6321d 100644
--- a/packages/stream_chat/lib/src/client.dart
+++ b/packages/stream_chat/lib/src/client.dart
@@ -764,7 +764,7 @@ class StreamChatClient {
     final updateData = _mapChannelStateToChannel(channels);
 
     await _chatPersistenceClient?.updateChannelQueries(
-      filter,
+      filter ?? {},
       channels.map((c) => c.channel!.cid).toList(),
       clearQueryCache: paginationParams.offset == 0,
     );
@@ -1434,7 +1434,11 @@ class ClientState {
 
   void _listenChannelHidden() {
     _subscriptions.add(_client.on(EventType.channelHidden).listen((event) {
-      _client.chatPersistenceClient?.deleteChannels([event.cid]);
+      final cid = event.cid;
+
+      if (cid != null) {
+        _client.chatPersistenceClient?.deleteChannels([cid]);
+      }
       if (channels != null) {
         channels = channels?..removeWhere((cid, ch) => cid == event.cid);
       }
diff --git a/packages/stream_chat/lib/src/db/chat_persistence_client.dart b/packages/stream_chat/lib/src/db/chat_persistence_client.dart
index 2dc2521c..07424299 100644
--- a/packages/stream_chat/lib/src/db/chat_persistence_client.dart
+++ b/packages/stream_chat/lib/src/db/chat_persistence_client.dart
@@ -39,32 +39,32 @@ abstract class ChatPersistenceClient {
   Future<List<String>> getChannelCids();
 
   /// Get stored [ChannelModel]s by providing channel [cid]
-  Future<ChannelModel> getChannelByCid(String? cid);
+  Future<ChannelModel> getChannelByCid(String cid);
 
   /// Get stored channel [Member]s by providing channel [cid]
-  Future<List<Member>> getMembersByCid(String? cid);
+  Future<List<Member>> getMembersByCid(String cid);
 
   /// Get stored channel [Read]s by providing channel [cid]
-  Future<List<Read>> getReadsByCid(String? cid);
+  Future<List<Read>> getReadsByCid(String cid);
 
   /// Get stored [Message]s by providing channel [cid]
   ///
   /// Optionally, you can [messagePagination]
   /// for filtering out messages
   Future<List<Message>> getMessagesByCid(
-    String? cid, {
+    String cid, {
     PaginationParams? messagePagination,
   });
 
   /// Get stored pinned [Message]s by providing channel [cid]
   Future<List<Message>> getPinnedMessagesByCid(
-    String? cid, {
+    String cid, {
     PaginationParams? messagePagination,
   });
 
   /// Get [ChannelState] data by providing channel [cid]
   Future<ChannelState> getChannelStateByCid(
-    String? cid, {
+    String cid, {
     PaginationParams? messagePagination,
     PaginationParams? pinnedMessagePagination,
   }) async {
@@ -99,8 +99,8 @@ abstract class ChatPersistenceClient {
   /// If [clearQueryCache] is true before the insert
   /// the list of matching rows will be deleted
   Future<void> updateChannelQueries(
-    Map<String, dynamic>? filter,
-    List<String?> cids, {
+    Map<String, dynamic> filter,
+    List<String> cids, {
     bool clearQueryCache = false,
   });
 
@@ -119,46 +119,46 @@ abstract class ChatPersistenceClient {
   Future<void> deletePinnedMessageByIds(List<String> messageIds);
 
   /// Remove a message by channel [cid]
-  Future<void> deleteMessageByCid(String? cid) => deleteMessageByCids([cid]);
+  Future<void> deleteMessageByCid(String cid) => deleteMessageByCids([cid]);
 
   /// Remove a pinned message by channel [cid]
   Future<void> deletePinnedMessageByCid(String cid) async =>
       deletePinnedMessageByCids([cid]);
 
   /// Remove a message by message [cids]
-  Future<void> deleteMessageByCids(List<String?> cids);
+  Future<void> deleteMessageByCids(List<String> cids);
 
   /// Remove a pinned message by message [cids]
   Future<void> deletePinnedMessageByCids(List<String> cids);
 
   /// Remove a channel by [cid]
-  Future<void> deleteChannels(List<String?> cids);
+  Future<void> deleteChannels(List<String> cids);
 
   /// Updates the message data of a particular channel [cid] with
   /// the new [messages] data
-  Future<void> updateMessages(String? cid, List<Message> messages);
+  Future<void> updateMessages(String cid, List<Message> messages);
 
   /// Updates the pinned message data of a particular channel [cid] with
   /// the new [messages] data
-  Future<void> updatePinnedMessages(String? cid, List<Message> messages);
+  Future<void> updatePinnedMessages(String cid, List<Message> messages);
 
   /// Returns all the threads by parent message of a particular channel by
   /// providing channel [cid]
-  Future<Map<String, List<Message>>> getChannelThreads(String? cid);
+  Future<Map<String, List<Message>>> getChannelThreads(String cid);
 
   /// Updates all the channels using the new [channels] data.
-  Future<void> updateChannels(List<ChannelModel?> channels);
+  Future<void> updateChannels(List<ChannelModel> channels);
 
   /// Updates all the members of a particular channle [cid]
   /// with the new [members] data
-  Future<void> updateMembers(String? cid, List<Member?> members);
+  Future<void> updateMembers(String cid, List<Member> members);
 
   /// Updates the read data of a particular channel [cid] with
   /// the new [reads] data
-  Future<void> updateReads(String? cid, List<Read> reads);
+  Future<void> updateReads(String cid, List<Read> reads);
 
   /// Updates the users data with the new [users] data
-  Future<void> updateUsers(List<User?> users);
+  Future<void> updateUsers(List<User> users);
 
   /// Updates the reactions data with the new [reactions] data
   Future<void> updateReactions(List<Reaction> reactions);
@@ -167,7 +167,7 @@ abstract class ChatPersistenceClient {
   Future<void> deleteReactionsByMessageId(List<String> messageIds);
 
   /// Deletes all the members by channel [cids]
-  Future<void> deleteMembersByCids(List<String?> cids);
+  Future<void> deleteMembersByCids(List<String> cids);
 
   /// Update the channel state data using [channelState]
   Future<void> updateChannelState(ChannelState channelState) =>
@@ -189,8 +189,9 @@ abstract class ChatPersistenceClient {
       deleteMembers,
     ]);
 
-    final channels =
-        channelStates.map((it) => it.channel).where((it) => it != null);
+    final channels = channelStates
+        .map((it) => it.channel)
+        .where((it) => it != null) as Iterable<ChannelModel>;
 
     final reactions = channelStates.expand((it) => it.messages).expand((it) => [
           if (it.ownReactions != null)
@@ -199,7 +200,7 @@ abstract class ChatPersistenceClient {
             ...it.latestReactions!.where((r) => r.userId != null)
         ]);
 
-    final users = channelStates
+    var users = channelStates
         .map((cs) => [
               cs.channel?.createdBy,
               ...cs.messages
@@ -215,7 +216,7 @@ abstract class ChatPersistenceClient {
               ...cs.members.map((m) => m.user),
             ])
         .expand((it) => it)
-        .where((it) => it != null);
+        .where((it) => it != null) as Iterable<User>;
 
     final updateMessagesFuture = channelStates.map((it) {
       final cid = it.channel!.cid;