Hi, did you solve this problem?
So found a solution for myself in 8 years old reddit topic.
- Check your log folder [yourproject]/Saved/Logs
My problem was in a parent shader that was using 17/16 samples.
Failed to compile Material for platform PCD3D_SM6, Default Material will be used in game.
Shader is using too many Samplers: 17 (only 16 supported)
- Open your failed material, and change Texture Sample > Sample Source > Shared:Wrap
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Since some smart people seem to have figured this out by now, could i please ask for some help to decipher this error message? 
I cant figure out what the material referred to even is. I find nothing when I search for it.
It’s the same problem as everyone else here had, it compiles shaders on every subframe rendered. 4 shaders, in my case. When i restart my engine the compiling goes away - until i use metahuman performance, which triggers the problem again.
Error from in engine output Log:
LogShaderCompilers: Warning: Failed to compile Material /Engine/Transient.ABView_Material for platform PCD3D_SM5, Default Material will be used in game.
/Engine/Generated/Material.ush:2756:8: warning: implicit truncation of vector type [-Wconversion]
return Result;
^
error: validation errors
zzz.dxil:19039:13: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%687 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %684, %dx.types.Handle %686, float %660, float %664, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#36’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:19035:13: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%678 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %675, %dx.types.Handle %677, float %660, float %664, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#35’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:19005:25: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%630 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %627, %dx.types.Handle %629, float %354, float %355, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#31’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:18997:24: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%621 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %618, %dx.types.Handle %620, float %354, float %355, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#30’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:18984:11: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%596 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %593, %dx.types.Handle %595, float %354, float %355, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#28’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:18980:11: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%583 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %580, %dx.types.Handle %582, float %354, float %355, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#26’ of function ‘?MaterialCHS@@YAXUFPackedMaterialClosestHitPayload@@UFRayTracingIntersectionAttributes@@@Z’.
Validation failed.
D3DCompileToDxil failed. Error code: Odefinierat fel (0x80004005).
zzz.dxil:20122:13: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%671 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %668, %dx.types.Handle %670, float %644, float %648, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#26’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:20118:13: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%662 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %659, %dx.types.Handle %661, float %644, float %648, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#25’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:20088:25: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%614 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %611, %dx.types.Handle %613, float %459, float %460, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#21’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:20080:24: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%605 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %602, %dx.types.Handle %604, float %459, float %460, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#20’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:20067:11: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%580 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %577, %dx.types.Handle %579, float %459, float %460, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#18’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
zzz.dxil:20063:11: error: Opcode Sample not valid in shader model lib_6_6(closesthit).
note: at ‘%567 = call %dx.types.ResRet.f32 @dx.op.sample.f32(i32 60, %dx.types.Handle %564, %dx.types.Handle %566, float %459, float %460, float undef, float undef, i32 0, i32 0, i32 undef, float undef)’ in block ‘#16’ of function ‘?PathTracingMaterialCHS@@YAXUFPackedPathTracingPayload@@UFRayTracingIntersectionAttributes@@@Z’.
I also have this problem on 5.4 with this error :
[2024.04.29-16.14.17:469][577]LogShaderCompilers: Warning: Failed to compile Material /Composure/Materials/Output/M_SrgbToLinear.M_SrgbToLinear for platform PCD3D_SM6, Default Material will be used in game.
/Engine/Generated/Material.ush:3340:24: error: condition for short-circuiting ternary operator must be scalar, for non-scalar types use ‘select’
return Color > 0.04045 ? pow( Color * (1.0 / 1.055) + 0.0521327, 2.4 ) : Color * (1.0 / 12.92);;
^
select(Color > 0.04045, pow(Color * (1. / 1.0549999999999999) + 0.052132699999999997, 2.3999999999999999), Color * (1. / 12.92))
I tried to delete the material function completely (which I don’t think is a good idea), and still get the error…
A lot of the actors are using this asset, most of them are PCG by the way
Any idea how to fix this ?
1 Like
Me too. 5.4
Guys… you’ve been given an answer and it is a correct one.
You have an offending shader in a material that is causing Unreal to replace it with a default shader and thus it has to recompile shader every frame.
Look at the log, find the offending material/s and fix it. If you can’t replace it and you won’t get the error.
It is not a bug, it is simply how engine works if it finds a bad material with shaders. It will try to fix it by replacing it and thus it will need to recompile the shaders.
As already answered:
Go to your project folder /Saved/Logs … find the latest log and look at the errors. It will tell you exactly the reason and which materials affect it.