unoplatform/uno · error · Exception

{type} compile failed: {infoLog}

Error message

{type} compile failed: {infoLog}

What it means

CompileShader in MRTBlitGlCanvasElement throws the shader info log when glCompileShader fails. For this MRT/MSAA sample, compile errors are usually the multi-output or blit-related GLSL constructs under a too-low shader version.

Source

Thrown at src/SamplesApp/SamplesApp.Samples/Windows_UI_Composition/MRTBlitGlCanvasElement.cs:310

			{
				throw new Exception("Program link failed: " + gl.GetProgramInfoLog(prog));
			}
			gl.DetachShader(prog, vs);
			gl.DetachShader(prog, fs);
			gl.DeleteShader(vs);
			gl.DeleteShader(fs);
			return prog;
		}

		private static uint CompileShader(GL gl, ShaderType type, string source)
		{
			var sh = gl.CreateShader(type);
			gl.ShaderSource(sh, source);
			gl.CompileShader(sh);
			gl.GetShader(sh, ShaderParameterName.CompileStatus, out int status);
			if (status != (int)GLEnum.True)
			{
				throw new Exception($"{type} compile failed: " + gl.GetShaderInfoLog(sh));
			}
			return sh;
		}
	}
}
#endif

View on GitHub (pinned to 0418340488)

Solutions

1. Read the info log line/column and fix the flagged construct.
2. Target #version 300 es / GL 330 for explicit MRT output locations.
3. Add precision qualifiers and ES built-ins.
4. Verify the shader source constant is complete.

Example fix

// before — ES2 single output, MRT needs explicit locations
#version 100
gl_FragData[0] = vec4(1);

// after
#version 300 es
precision mediump float;
layout(location=0) out vec4 fragColor0;
layout(location=1) out vec4 fragColor1;

if (fragmentSource.Contains("layout(location=") && !fragmentSource.Contains("#version 300"))
    throw new InvalidOperationException("Explicit MRT output locations require #version 300 es / GL 330.");

try { return CompileShader(gl, type, source); }
catch (Exception ex) { throw new InvalidOperationException($"{type} compile failed: {ex.Message}\n{source}", ex); }

When it happens

Trigger: `layout(location=0) out vec4` under #version 100 (ES2); gl_FragData indexing on a context with one slot; missing precision qualifier; unknown built-in used in the blit/resolve shader.

Common situations: Sample on WebGL1 where explicit output locations are unsupported; shader copied from desktop GL into ES; truncated source string.

Related errors

• Program link failed: {infoLog}
• Program link failed: {infoLog}
• {type} compile failed: {infoLog}
• Program link failed: {infoLog}
• {type} compile failed: {infoLog}

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/d053c080b4507917. Report an issue: GitHub.