# Crash in ChannelListFragment **URL:** \ **Category:** Android\ **Tags:** group-channel, chatsdk\ **Created:** [January 30, 2022, 4:36pm UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865 "2022-01-30T16:36:25Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![Vladislav\_Karpman](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/vladislav_karpman/32/1860_2.png) [@Vladislav\_Karpman](https://community.sendbird.com/u/Vladislav_Karpman)\ **Post date:** [January 30, 2022, 4:36pm UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/1 "2022-01-30T16:36:25Z")
Hi! I use the latest version of UIKit (com.sendbird.sdk:uikit:2.2.3), and I have crash in production when user switches between `ChannelListFragment` and other fragment a bit fast than regular user. This the log of the crash: ```auto E/AndroidRuntime: FATAL EXCEPTION: main Process: health.alike.app, PID: 11531 java.lang.NullPointerException: Attempt to invoke interface method 'void com.sendbird.android.handlers.GroupChannelCollectionHandler.onChannelsUpdated(com.sendbird.android.handlers.GroupChannelContext, java.util.List)' on a null object reference at com.sendbird.android.GroupChannelCollection$7.run(GroupChannelCollection.java:542) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loop(Looper.java:223) at android.app.ActivityThread.main(ActivityThread.java:7656) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:592) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:947) ``` Likely it happens inside `ChannelListViewModel`. Also, I noticed that when a user switches between fragments a bit faster `initChannelCollection()` and `disposeChannelCollection()` don’t go one after another as they supposed to. Hence, I think that’s why crash appears: ```auto D/SBUIKIT: [19:21:11.812 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() D/SBUIKIT: [19:21:11.959 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() D/SBUIKIT: [19:21:12.292 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() D/SBUIKIT: [19:21:12.745 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() ``` Normal call stack is supposed to look like this: ```auto D/SBUIKIT: [19:32:46.707 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() D/SBUIKIT: [19:32:48.123 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() D/SBUIKIT: [19:32:49.775 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() D/SBUIKIT: [19:32:50.848 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() ``` ---
**Author:** ![Woo](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/woo/32/125_2.png) [@Woo](https://community.sendbird.com/u/Woo)\ **Post date:** [January 31, 2022, 8:13am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/2 "2022-01-31T08:13:20Z")
@Vladislav_Karpman thanks for the reporting! I will let our android team to know and get back to you soon ---
**Author:** ![Vladislav\_Karpman](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/vladislav_karpman/32/1860_2.png) [@Vladislav\_Karpman](https://community.sendbird.com/u/Vladislav_Karpman)\ **Post date:** [January 31, 2022, 10:28am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/3 "2022-01-31T10:28:23Z")
@Woo It’s a pretty much important since we’re having crash in production. Hopefully, soon you will find a solution ---
**Author:** ![LeoShin](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/leoshin/32/397_2.png) [@LeoShin](https://community.sendbird.com/u/LeoShin)\ **Post date:** [February 3, 2022, 12:56am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/4 "2022-02-03T00:56:51Z")
@Vladislav_Karpman Thank you for reporting!. - NPE problem has been fixed, and it will be released next regular release. And regarding the problem of order, there are two cases where A is disposed. - If an existing collection exists when trying to retrieve a channel list through the loadInitial, previous collection will dispose - If the View Model is clear, it is disposed. So please check if `loadInitial` is being called twice in a row. ---
**Author:** ![Vladislav\_Karpman](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/vladislav_karpman/32/1860_2.png) [@Vladislav\_Karpman](https://community.sendbird.com/u/Vladislav_Karpman)\ **Post date:** [February 3, 2022, 9:16am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/5 "2022-02-03T09:16:33Z")
@LeoShin Thanks! Hopefully the issue is resolved. Regarding your comment: `loadInitial()` is private method and is under UIKit control, so you have to make sure that order is correct. ---
**Author:** ![LeoShin](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/leoshin/32/397_2.png) [@LeoShin](https://community.sendbird.com/u/LeoShin)\ **Post date:** [February 3, 2022, 11:52am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/6 "2022-02-03T11:52:41Z")
> [@Vladislav\_Karpman](#): > > ```auto > D/SBUIKIT: [19:21:11.812 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() > D/SBUIKIT: [19:21:11.959 ChannelListViewModel:initChannelCollection():36] >> ChannelListViewModel::initChannelCollection() > D/SBUIKIT: [19:21:12.292 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() > D/SBUIKIT: [19:21:12.745 ChannelListViewModel:disposeChannelCollection():45] >> ChannelListViewModel::disposeChannelCollection() > > ``` **loadInitial** , which I mentioned above, is a method of the ChannelListViewModel, which is a public method. Since the initChannelCollection from the log is called only when **loadInitial** is called, I was wondering when **loadInitial** is called. How can I reproduce what’s shown in the log? ---
**Author:** ![Vladislav\_Karpman](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/vladislav_karpman/32/1860_2.png) [@Vladislav\_Karpman](https://community.sendbird.com/u/Vladislav_Karpman)\ **Post date:** [February 3, 2022, 4:49pm UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/7 "2022-02-03T16:49:38Z")
I have 2 fragments: One is just regular fragment from our app and another one is ChannelListFragment. If I start switching between these 2 fragments pretty fast, I will get error pretty soon. ---
**Author:** ![LeoShin](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/leoshin/32/397_2.png) [@LeoShin](https://community.sendbird.com/u/LeoShin)\ **Post date:** [February 4, 2022, 12:21am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/8 "2022-02-04T00:21:50Z")
We will include this in the regular release. The regular release will be around mid-February. ---
**Author:** ![Vladislav\_Karpman](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/vladislav_karpman/32/1860_2.png) [@Vladislav\_Karpman](https://community.sendbird.com/u/Vladislav_Karpman)\ **Post date:** [February 6, 2022, 8:38am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/9 "2022-02-06T08:38:33Z")
Thanks, hopefully it will be fixed ---
**Author:** ![LeoShin](https://sea2.discourse-cdn.com/flex020/user_avatar/community.sendbird.com/leoshin/32/397_2.png) [@LeoShin](https://community.sendbird.com/u/LeoShin)\ **Post date:** [February 17, 2022, 9:03am UTC](https://community.sendbird.com/t/crash-in-channellistfragment/3865/10 "2022-02-17T09:03:42Z")
We have released v2.2.4 uikit that fixed this issue today. please check it out. hopefully, it will have been fixed.