Happens in 4.8.1 whenever I try to run a 2 person standalone game.
Hey T3CHZ,
Are you running Marketplace project Generic Shooter?
Yes, I am.
Having same issue with a personal project since update to 4.8.1. Only happening when I uncheck “single process”.
Thanks rXp. T3CHZ, can you check your Editor Preferences > Play and see whether Use Single Process is enabled? Thanks!
" Use single process " was enabled, I disabled it and saved my game but still get same error. I restarted editor and problem still occurs. Disabling " Use single process " unfortunately does not seem to fix this issue.
Okay, generally you should make sure Use Single Process is enabled, so you can set that back to enabled for now.
Can you up project and upload it somewhere so I can take a look? Once you do, please PM me link via forums:
Okay, I have done that now.
This also occurs when running on dedicated server and Use Single Process is enabled. (only 1 player)
One last thing I’d like you all to try:
Open Editor Preferences > Play and disable Use Single Process. Then, make sure Editor Multiplayer Mode is set to Play Offline. Then enable Use Single Process again. Let me know whether issue still occurs.
Okay, it sounds like even while Use Single Process is still disabled, it still pulls from Editor Multiplayer Mode, which it should not do. There seems to be an issue while Use Single Process is disabled, and I’m going to write that up.
For now, you can test in Standalone with multiple players by using a shortcut to UE4Editor.exe and pointing it to your project. Open up properties of shortcut, and in Target field, add location of your .uproject file followed by " -game". For most, it’ll look like this:
“C:\Program Files\Epic Games\4.8\Engine\Binaries\Win64\UE4Editor.exe” “C:\Users.\Documents\Unreal Projects\MultiplayerShootout2\MultiplayerShootout2.uproject” -game
Open up two of those and you should be able to connect with no problems. I’ll post here again when I’ve finished investigating this bug.
it does not give me this error with your setup, but now it only launches 1 window instead of 2.
Hi all,
As mentioned above, there appears to be two problems: 1. Having Use Single Process disabled can cause this error, and 2. if Use Single Process is enabled but Editor Multiplayer Mode was previously set to anything other than Play Offline, editor will still Play as if Use Single Process is disabled. It appears that both Multiplayer Shootout and Generic Shooter projects had at one point disabled Use Single Process and switched from Play Offline to Play as Listen Server, which would cause problem 1 to occur even if Use Single Process was re-enabled.
I have entered two bug reports for these: UE-18071 and UE-18074 respectively. I’ll update this post when I see any update on it.
In meantime, as mentioned above, you can simply disable Use Single Process in Editor Preferences > Play, then make sure Editor Multiplayer Mode is set to Play Offline, then enable Use Single Process again. If you need to test in Standalone with two windows, you’ll need to set up a shortcut to editor as described above.
Hope that helps! Thank you all for help reproducing this!
Thank you so much for looking into this , I really appreciate you taking time to help us out with this bug. Looking forward to a permanent fix one day, and for now workaround solution you have given us works just fine 
Thanks for figuring this out and solving this, been a bit busy and have been getting a few questions regarding this and I haven’t been able to repro it at all, not sure why.
Allar! I actually meant to contact you about this sometime today. I believe easiest fix is to make sure Editor Multiplayer Mode is set to Play Offline before enabling Use Single Process, and then new users shouldn’t experience this anymore. I’m not 100% up on Marketplace content update process, but that should be all your users need when they contact you. If that doesn’t do it, please let us know!
I am encountering this same issue. I’m on a mac version 4.10.1 running the ‘Realistic Rendering’ demo from Unreal. Trying to package and default to night map. I get error: "map specified on command line ‘/Game/Maps/RoomNight’ could not be found Exiting.
Any thoughts? I tried suggestions above (Play Offline Use Single Process etc) and no luck.
Hi sebastiansgames,
Can you create a new post for this? Since it’s a different content pack and suggested workaround doesn’t help, I don’t believe it’s related. Once you have a new Bug Reports post up, I can get right people to look into it. Thank you!
Okay i’ve posted a new thread here:
Edit → Project Settings → Maps and Modes
Under Default Maps, try changing ‘Game Default Map’ to an existing map ( starting one).
Or try going into your DefaultEditor.ini and changing Simple Map.