# Replay System breaks Character Movement after 4.12 upgrade

**URL:** <https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895>\
**Category:** Multiplayer & Networking\
**Tags:** Networking, replay-system, network-replay, unreal-engine, CPP, question\
**Created:** [August 2, 2016, 5:11pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895 "2016-08-02T17:11:21Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![Frozenfire](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Frozenfire](https://forums.unrealengine.com/u/Frozenfire)\
**Post date:** [August 2, 2016, 5:11pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/1 "2016-08-02T17:11:21Z")

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I have been using replay system since 4.10. Everything seems to be working fine.

However after upgrade to 4.12, it seems to be broken in a very strange way. The bad news is that , even the way it is broken is not consistent. I’m at my wit’s end on what’s going on . Here’s a video of how it’s behaving.

4.12 ( broken )

[![]( " - YouTube") ](https://www.youtube.com/watch?v=BG7rFrVXQXA)

4.11 (more or less same scenario , works perfect )

[![]( " - YouTube") ](https://www.youtube.com/watch?v=br-HPIqpMHQ)

i spend the last 2 days diagnosing this here’s what I discovered / tried ;

- I removed all root animations from animation sequence. Didn’t work still.
- I have tried uncooked/development/shipping. None works.
- I have tried recording from server and client. With or without any player joining. Same result
- Movement seems to be working for player. Note that the player / AI extends from the same char class. And both AI and player works in 4.10/4.11 absolutely flawlessly.

In multiplayer game it worked fine. Character movement are correct and flawless. I’m sure it’s not normal replication issue. but I do notice however that 4.12 have its own changes on replication. Hence if someone can guide me on where else I can look would be great. But right now it seem so strange.

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**Author:** ![anonymous\_user\_61b4a355](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_61b4a355](https://forums.unrealengine.com/u/anonymous_user_61b4a355)\
**Post date:** [August 2, 2016, 6:54pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/2 "2016-08-02T18:54:19Z")

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Hey Frozenfire,

Just to clarify some things:

- Does the movement break after using the replay system? Or, does the movement break when the replay system is enabled but not used?
- Is the 4.12 ( broken ) video of a replay?
- Do you have any insight on how to recreate the issue?

Thanks.

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<div class="post-metadata">

**Author:** ![Frozenfire](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Frozenfire](https://forums.unrealengine.com/u/Frozenfire)\
**Post date:** [August 2, 2016, 6:57pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/3 "2016-08-02T18:57:40Z")

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- Normal gameplay is perfectly fine.
- Both are videos of replay.
- I need to have some clue on what’s causing it in order to attempt to  
create it. My first suspicion was roorootmation but that was ruled  
out.

I assume there’s no known issue on this at the moment?

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**Author:** ![anonymous\_user\_61b4a355](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_61b4a355](https://forums.unrealengine.com/u/anonymous_user_61b4a355)\
**Post date:** [August 2, 2016, 7:05pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/4 "2016-08-02T19:05:10Z")

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I don’t see any known issue reports on this but I am working on seeing if I can replicate it.

If you discover anything on your end please update this post. I will do the same if I figure anything out.

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**Author:** ![anonymous\_user\_61b4a355](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_61b4a355](https://forums.unrealengine.com/u/anonymous_user_61b4a355)\
**Post date:** [August 2, 2016, 7:51pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/5 "2016-08-02T19:51:11Z")

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Hey Frozenfire,

Thank you for submitting a bug report. I have reproduced this issue and logged a report for it here: [https://issues.unrealengine.com/issue/UE-34097](https://issues.unrealengine.com/issue/UE-34097). You can track the report’s status as the issue is reviewed by our development staff.

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**Author:** ![Frozenfire](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Frozenfire](https://forums.unrealengine.com/u/Frozenfire)\
**Post date:** [August 2, 2016, 7:53pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/6 "2016-08-02T19:53:41Z")

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Just a quick question. I am aware that paragorn has ai mobs as well. Are they doing anything differently? It seems they have it in quite a large number as well

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<div class="post-metadata">

**Author:** ![anonymous\_user\_61b4a355](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_61b4a355](https://forums.unrealengine.com/u/anonymous_user_61b4a355)\
**Post date:** [August 2, 2016, 8:02pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/7 "2016-08-02T20:02:12Z")

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Paragons development is separate from the engine development so I am unable to say for certain if they are having this issue or not. I can say that in the past, if there is a fix for a bug, it may be merged into the engines main branch when cleared by QA.

Keep an eye on the issue page. There should be an update on that whenever a developer has time to look at it.

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**Author:** ![anonymous\_user\_53648559](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_53648559](https://forums.unrealengine.com/u/anonymous_user_53648559)\
**Post date:** [August 2, 2016, 9:58pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/8 "2016-08-02T21:58:01Z")

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I just wanted to post that we have seen this internally, and this may or may not fix it, but I wanted to post this to make sure:

Find this code in DemoNetDriver.cpp:

```
	if (!bDidReplicateActor)
	{
		// Clear external data if the actor didn't replicate for some reason
		PropertyTracker->ExternalData.Empty();
		PropertyTracker->ExternalDataNumBits = 0;
	}

```

And changed to:

```
	if ( !GuidCache->NetGUIDLookup.Contains( Actor ) )
	{
		// Clear external data if the actor has never replicated yet (and doesn't have a net guid)
		PropertyTracker->ExternalData.Empty();
		PropertyTracker->ExternalDataNumBits = 0;
	}

```

This change should be included in the next 4.13 release.

Let us know if that doesn’t work!

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<div class="post-metadata">

**Author:** ![Frozenfire](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Frozenfire](https://forums.unrealengine.com/u/Frozenfire)\
**Post date:** [August 3, 2016, 4:29am UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/9 "2016-08-03T04:29:39Z")

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Does this require full source? I am working from binary build. In guessing it’s not possible to change that right

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<div class="post-metadata">

**Author:** ![anonymous\_user\_61b4a355](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@anonymous\_user\_61b4a355](https://forums.unrealengine.com/u/anonymous_user_61b4a355)\
**Post date:** [August 3, 2016, 12:56pm UTC](https://forums.unrealengine.com/t/replay-system-breaks-character-movement-after-4-12-upgrade/365895/10 "2016-08-03T12:56:29Z")

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fix would require the source code.

If you want to know more regarding it, you can start here:

[][1]

[1]: