same problem in 4.23p7.
Do this…
- Compile Engine as you would. (Re-Generate Project Files before Compiling).
- Generate Project Files for the Project you want to Compile.
- Then Right Click your Project which should appear Under “Games” in Visual Studio. Project Only > Build “Project Name”.
And all errors will go away. 
Answer Hub is not used for bug reports, you should use the bug submission form if you’d like to have more chance of anything being fixed: Unreal Engine Community
And did you report it via the form?
@Gomo/ChristopheK. - I have found that there is a great benefit to these RAYTRACING postings because it keeps everyone up to speed and aware of the issues, while potentially yielding discussion on workarounds.
I learned through this thread it would not be functional to bombard the developers with Raytracing support tickets as development is not even be able to address the issues with Raytracing right now. It is an in-development quasi-Beta feature that is not yet ready.
(See earlier posts in this thread by Nilson Lima on this topic, he provides a lot of assistance and was able to comment on how Epic is struggling with the Raytracing shadow issue as it was a built from scratch render engine. Apparently they have no prioritized projected time frame for a resolution with the Raytraced shadow issues.)
I have seen this also from time to time, without really being able to find a pattern, almost seems to be a general stability phenomenon with Raytracing.
Maybe we can find a pattern here -
What GPU? (RTX vs non-RTX)
Scene? (Complex vs not-Complex)
I think you didn’t read my previous answer at https://forums.unrealengine.com/unre…87#post1651087, but nowhere I affirmed Epic devs are struggling, but it is an effort that for the sanity has to be released on steps. Right now you can have raytracing working as solution, not 100%, but mixed. It is hard to do it? Yes, but the Troll Demo film was made with the tools released for the public, so it is a matter of finding how. I am not even worried about shadows right now regarding realtime raytracing, what really worries me is how is going to be handled the translucency at reflections, currently not working at all, and I have special needs into this matter.
Also, I don’t agree that support tickets should be refrained, on the opposite, everyone finding an issue must report it. There are people at Epic to analyze the reports, check if reproducible and not repeated, and to redirect them to the devs behind the features being reported, so not the main devs themselves deal with screening out the issues, that would be insane.
Thanks! I totally forgot about that.
In my case - I am considering switching from VXGI to Raytracing in my project, so this particular feature is crucial for this.
Sadly that doesn’t reduce it enough to get it close to where it was before the upgrade. And if that’s going to continue to be the case, we’re stuck in 4.22 till they reduce it again. A 200mb increase is not justifiable to our customers when there is nothing to gain from it.
*Preview 7 for 4.23 Apply and Receive Damage not working ( When new initialization, not update to * 4.23P6)
4.23 P7 Vertex Snapping error.
What I hope is a tiny bit of good news for the engineers toiling away on 4.23, I’m making use of preview 7 for the betatest branch of my project. I can see that GI behaves differently, and ray tracing seems more stable. In 4.22 RT shadows would sometimes just fail. Randomly shadows wouldn’t be there or they would only be there for some objects. Looks like that might be fixed now.
I’m still developing in 4.22, then I drop the latest Content folder into a copy of the project for 4.23p7 and I’m able to generate a build in a few steps. The only issue I’ve run into is one map has a large number of foliage meshes which runs real slow in 4.23p7. But I saw from the siggraph talk that dealing with and supporting foliage in a RT scene is a known challenge, so I’m not worried about this. Everything is working pretty smoothly and the ease of transition to the preview build has allowed me to generate playable builds. Very happy with all this! 
Whenever I try to launch 4.23 I get this:
I can’t remember installing anything called “BlastPlugin”. What is this? Can I just delete it? I think I’m just going to delete it.
Same here, did you find a solution?
Only the default example HDRI by Epic is sharp, and that’s only 4K. What setting are we missing? Why didn’t this work seamlessly?
Also, the HDRIBackdrop complains that another skylight is active, but if I remove that skylight (and directional light), my entire scene becomes black. So this is RTX only? That’s rather unfortunate if that’s the case. I saw a Youtube video demonstration where a guy from Epic used this in a helicopter scene on an iPad. Again, I wonder what setting I am missing?
If I remember correctly, HDR images get set to maximum res of 256, by default. So even if it is 4k or something like that, you have to set the maximum size for the texture in the texture properties window (double click the texture).
Is any body have similar problem? In 4.23 Sample Pseudo Volume Texture doesn’t work. A think, its related to texture management.
https://forums.unrealengine.com/development-discussion/rendering/1596383-fx-niagara-pseudo-volume-texture
is RT GT still broken in preview 7?
I’m not sure what you mean by broken. I’m making use of it (as an option to turn on/off) and I think its fine in most cases with the right settings. I’m sure they don’t consider it to be final or as good as it can be.
i am very happy for the result (auto generated uv)
Sorry currently busy with work so no time to test 4.23, someone mention it wasn’t working in preview 5/6, can you post some screenshot of the feature(RT GI)? Is the sampling better(less noise in the denoiser)?
It’s there and working, but the denoiser still produces WIP results. The behavior does look different to me than 4.22.3, might be better in some cases, but I wouldn’t say it looks perfect yet. I’ve settled on some particular settings that are giving me decent results until RTGI can be finished.