# Custom object line trace don't work on mobile? **URL:** \ **Category:** Mobile\ **Tags:** line-trace, Mobile, unreal-engine, Blueprint, question\ **Created:** [May 20, 2015, 3:23pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235 "2015-05-20T15:23:02Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 3:23pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/1 "2015-05-20T15:23:02Z")
I’ve made a custom object and I am using a single line trace for that object type only, but on mobile preview it wont work. and on my phone it crashes when I try to trace… I tried setting on draw debug type and used the mobile preview. It didn’t give me any trace… ---
**Author:** ![wittlief\_1](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@wittlief\_1](https://forums.unrealengine.com/u/wittlief_1)\ **Post date:** [May 20, 2015, 6:41pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/2 "2015-05-20T18:41:07Z")
Hi fanzypantz, We’re going to need more information before we can begin providing assistance for you. [Please have a look at this AnswerHub thread](https://answers.unrealengine.com/questions/12363/how-do-i-report-a-bug.html) for a template of what info we’re going to need. Thanks! ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 8:03pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/3 "2015-05-20T20:03:20Z")
Where do I find the crashlogs on the mobile deployment? Now I am using an Samsung Note 2(GT- N7100) Android 4.4.2 I am tracing for a custom object channel trough the pawn blueprint and every-time I try to do that part of the blueprint the game crashes on mobile. I cant duplicate it on a new project. On PC: It works, no problems On PC Mobile Preview: no crash, not working. On Mobile: instant crash. The trace is directly on the pawn event graph. I can’t see anything directly wrong with the blueprinting, but I don’t know the limitations of Mobile blueprinting. ---
**Author:** ![Slayemin](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Slayemin](https://forums.unrealengine.com/u/Slayemin)\ **Post date:** [May 20, 2015, 8:27pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/4 "2015-05-20T20:27:37Z")
I know there’s a bug with the “line trace by channel” not intersecting when it should about 5-10% of the time. The fix for that is using the “Sphere Trace by Channel”. Have you tried switching to the sphere trace to see if it crashes as well? ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 8:52pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/5 "2015-05-20T20:52:58Z")
I switched it out for a sphere trace. I’m not really sure what is wrong. The only thing that happens afterwards is a few variables that get set and small one cast node. It’s my first mobile game try, so I’m sure I’ve missed something… Like UMG don’t seem to work. ---
**Author:** ![Slayemin](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Slayemin](https://forums.unrealengine.com/u/Slayemin)\ **Post date:** [May 20, 2015, 9:47pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/6 "2015-05-20T21:47:35Z")
Does it still crash, or are you able to get past the crash? If it still crashes, either both traces cause issues, or no traces cause issues and the cause of the crash is elsewhere. If it doesn’t crash anymore, then we have isolated the crash to the line trace by channel as the cause. ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 9:53pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/7 "2015-05-20T21:53:32Z")
oh it crashed, I’ll do some more testing and come back in a min. ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 9:59pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/8 "2015-05-20T21:59:04Z")
first I cut the thing after the trace, crash… Then I cut the trace off completely, no crash. So I seem to have a problem with the trace. ---
**Author:** ![Slayemin](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Slayemin](https://forums.unrealengine.com/u/Slayemin)\ **Post date:** [May 20, 2015, 10:01pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/9 "2015-05-20T22:01:26Z")
Hmm, okay. Sounds like you’re going to have to add a crash log so that the epic devs can figure out what exactly is causing the traces to crash. ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 10:03pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/10 "2015-05-20T22:03:03Z")
where exactly on my phone do I find the log? thanks for the help btw ---
**Author:** ![Slayemin](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Slayemin](https://forums.unrealengine.com/u/Slayemin)\ **Post date:** [May 20, 2015, 10:41pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/11 "2015-05-20T22:41:11Z")
Look in your game directory. There should be a “Saved” folder. In there, you should see something that has your game name with a .log file extension. This is what you want to see & send. ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 20, 2015, 10:57pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/12 "2015-05-20T22:57:52Z")
[http://puu.sh/hUHMa/a1731c9942.log](http://puu.sh/hUHMa/a1731c9942.log) This was the only log I found. I did however figure out that on PC Mobile Preview the trace actually works but always give me a false even though it should hit(it does on PC) Edit; it gives me false with or without custom object type… ---
**Author:** ![Slayemin](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Slayemin](https://forums.unrealengine.com/u/Slayemin)\ **Post date:** [May 20, 2015, 11:12pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/13 "2015-05-20T23:12:42Z")
Yeah, I don’t see anything there which jumps out at me. Check out this link and see if it helps you find any other crash logs: > **[A new, community-hosted Unreal Engine Wiki](https://forums.unrealengine.com/t/a-new-community-hosted-unreal-engine-wiki/141494)** > > After over a year in maintenance mode, the official Unreal Engine Wiki is now permanently offline. These resources now live on a new community-run Unreal Engine Community Wiki — ue4community.wiki! You will be able to find content from the official... ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 21, 2015, 11:17pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/14 "2015-05-21T23:17:04Z")
I’ve done more work since, but I am crashing on startup this time: I used android monitor and this is the log from when I try to launch it: [http://puu.sh/hVQoa/ac094bc33c.txt](http://puu.sh/hVQoa/ac094bc33c.txt) ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 21, 2015, 11:17pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/15 "2015-05-21T23:17:11Z")
I’ve done more work since, but I am crashing on startup this time: I used android monitor and this is the log from when I try to launch it: [http://puu.sh/hVQoa/ac094bc33c.txt](http://puu.sh/hVQoa/ac094bc33c.txt) ---
**Author:** ![wittlief\_1](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@wittlief\_1](https://forums.unrealengine.com/u/wittlief_1)\ **Post date:** [May 22, 2015, 3:40pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/16 "2015-05-22T15:40:03Z")
Hi fanzypantz, I noticed references to some ‘failed to read’ file errors right before your crash, like this: > LogStreaming:Warning: Failed to read > file > ‘…/…/…/Engine/Content/Editor/Slate/Common/TableViewHeader.png’ > error. and while I do think those are going to be a problem for your project, I don’t think that’s what is causing your crash. What I think it is, is this: > 05-22 01:13:57.791: D/UE4(1552): Fatal > error: > [File:D:\BuildFarm\buildmachine\_++depot+UE4-Releases+4.8\Engine\Source\Runtime\Engine\Private\AI\Navigation\NavCollision.cpp] > [Line: 438] 05-22 01:13:57.791: > D/UE4(1552): Attempt to build nav > collision data for > /Game/Meshes/Bus\_mid.Bus\_mid:NavCollision\_0 > when we are unable to. This platform > requires cooked packages. 05-22 > 01:13:57.791: D/UE4(1552): > [2015.05.21-23.13.57:798][ > 0]Assertion failed: Assertion failed: > [File:D:\BuildFarm\buildmachine\_++depot+UE4-Releases+4.8\Engine\Source\Runtime\Engine\Private\AI\Navigation\NavCollision.cpp] > [Line: 438] 05-22 01:13:57.791: > D/UE4(1552): Attempt to build nav > collision data for > /Game/Meshes/Bus\_mid.Bus\_mid:NavCollision\_0 > when we are unable to. This platform > requires cooked packages. This appears to be a setup problem since UE4 cannot generate a navmesh dynamically for Android; it requires precooked content. For your reference, here is the [Mobile Development documentation](https://docs.unrealengine.com/latest/INT/Platforms/Mobile/index.html). Hope that helps! ---
**Author:** ![fanzypantz](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@fanzypantz](https://forums.unrealengine.com/u/fanzypantz)\ **Post date:** [May 22, 2015, 4:06pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/17 "2015-05-22T16:06:59Z")
Thanks, that combated my crash on load, but still crashes on tracing. Here is the log from when this happens; Just search for: “Swipe Right Event” and the crash happens right after that. There is quite a few errors, and the slate thing might be related to why my UMG doesn’t show up? ---
**Author:** ![wittlief\_1](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@wittlief\_1](https://forums.unrealengine.com/u/wittlief_1)\ **Post date:** [May 28, 2015, 2:15pm UTC](https://forums.unrealengine.com/t/custom-object-line-trace-dont-work-on-mobile/319235/18 "2015-05-28T14:15:06Z")
Hi Fanzypantz, One of the common elements I see in both your UE4 logs and your monitor logs is ‘BP\_Character\_C’, which might be the root cause of your issues. Here are the affected BP elements from your editor logs: > BP\_Character\_C.ExecuteUbergraph\_BP\_Character > BP\_Character\_C.Swipe Left Event > BP\_Character\_C.ExecuteUbergraph\_BP\_Character > BP\_Character\_C.InpTchEvt\_EdGraphPin\_6620 [Here is another AnswerHub thread](https://answers.unrealengine.com/questions/155886/blueprint-events-crash-packaged-game.html) wherein a user was experiencing the same error on crash (Assertion failed: Result [File:Runtime/CoreUObject/Public/UObject\Stack.h] [Line: 225]) and the JIRA report logged for same (UE-7872) which is still being fixed. Luckily, Doug Wilson was able to provide a workaround for the other user that might work for you. Good luck!