What It Means & How to Fix It in UE5

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🧠 Why You’re Seeing This Error

This error means Unreal Engine couldn’t match the parameter bindings between your C++ shader class and your HLSL .usf file.

It typically happens when:

• You declare a parameter in C++ that doesn’t exist in the shader
• You rename or remove a parameter from the shader but don’t update the C++ bindings
• Your SetParameters() logic binds the wrong type or name
• There’s a layout or precision mismatch between your C++ FShaderParameterStruct and the HLSL side

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💥 Example Error Message

LogShaderBinding: Error: Binding mismatch between shader and C++ parameters: 'MyCustomParameter' not found in shader

Or:

Fatal error: Shader parameter 'MyBuffer' expected, but not declared in shader file

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🛠️ Common Shader Scenarios That Trigger This

❌ Declaring a Parameter in C++ That Doesn’t Exist in HLSL

MyShader.SetShaderValue(RHICmdList, ShaderRHI, MyFloatParam, 1.0f); // ❌ No such param in HLSL

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❌ Mismatched Parameter Name Between HLSL and C++

HLSL:

float MyValue;

C++:

FShaderParameter MyFloatValue; // ❌ different name than MyValue

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❌ Mismatched Buffer Struct Layouts

If you’re using TUniformBufferRef<FMyShaderParams>, the struct must exactly match between C++ and shader code:

// C++
BEGIN_SHADER_PARAMETER_STRUCT(FMyShaderParams, )
    SHADER_PARAMETER(float, Radius)
END_SHADER_PARAMETER_STRUCT()

// HLSL
cbuffer MyShaderParams
{
    float Radius;
}

If you rename the buffer in HLSL or mismatch the contents, binding fails.

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✅ How to Fix Binding Mismatches – Step-by-Step

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✔️ 1. Double-Check That All C++ Parameters Exist in the Shader File

If you bind a parameter in SetParameters(), confirm it is declared in .usf:

float Radius; // ✅ must exist if bound from C++

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✔️ 2. Match Parameter Names Exactly (Case-Sensitive)

If your HLSL uses:

float LightPower;

Your C++ should be:

FShaderParameter LightPower;

✅ No mismatches, no typos
❌ Avoid using lightPower, light_power, etc.

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✔️ 3. Use SHADER_PARAMETER and SHADER_PARAMETER_STRUCT Macros Correctly

C++:

BEGIN_SHADER_PARAMETER_STRUCT(FMyParams, )
    SHADER_PARAMETER(float, GlowAmount)
END_SHADER_PARAMETER_STRUCT()

HLSL:

cbuffer MyParams
{
    float GlowAmount;
};

The name of the cbuffer (MyParams) and field (GlowAmount) must match.

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✔️ 4. Recompile After Changes

After making changes to your shader or parameter bindings, recompile:

- Restart UE5
- Delete DerivedDataCache/
- Or run: ShaderCompileWorker -clean

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✅ Summary: How to Fix “Binding Mismatch Between Shader and C++ Parameters” in UE5

Cause	Fix
Parameter missing in .usf file	Add the matching variable declaration to your HLSL shader
Name mismatch	Ensure exact match between C++ and HLSL names (case-sensitive)
Incorrect struct layout	Match SHADER_PARAMETER_STRUCT with cbuffer in HLSL exactly
Binding unused or old parameter	Remove or update unused SetShaderValue() calls in C++