unoplatform/uno · error · Exception

Program link failed: {infoLog}

Error message

Program link failed: {infoLog}

What it means

CreateProgram in IntAttribsBlendGlCanvasElement links compiled vertex/fragment shaders and throws the program info log if LinkStatus != True. This instancing+blend sample uses integer vertex attributes, so link failures commonly stem from integer-attribute or instancing feature gaps in the active GLSL profile.

Source

Thrown at src/SamplesApp/SamplesApp.Samples/Windows_UI_Composition/IntAttribsBlendGlCanvasElement.cs:247

			gl.Disable(EnableCap.Blend);
			gl.BlendEquationSeparate(BlendEquationModeEXT.FuncAdd, BlendEquationModeEXT.FuncAdd);
			gl.SampleCoverage(1f, false);

			Invalidate();
		}

		private static uint CreateProgram(GL gl, string vertexSource, string fragmentSource)
		{
			var vs = CompileShader(gl, ShaderType.VertexShader, vertexSource);
			var fs = CompileShader(gl, ShaderType.FragmentShader, fragmentSource);
			var prog = gl.CreateProgram();
			gl.AttachShader(prog, vs);
			gl.AttachShader(prog, fs);
			gl.LinkProgram(prog);
			gl.GetProgram(prog, ProgramPropertyARB.LinkStatus, out int linkStatus);
			if (linkStatus != (int)GLEnum.True)
			{
				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));
			}

View on GitHub (pinned to 0418340488)

Solutions

1. Read the info log for the unresolved symbol or attribute.
2. Use #version 300 es / GL 330+ for integer attributes and instancing.
3. Match integer `out`/`in` varyings exactly between vertex and fragment.
4. Avoid reading an integer varying as float in the fragment stage.

Example fix

// before — integer attribute declared under ES2
#version 100
attribute ivec4 aCell; // unsupported → link fail

// after
#version 300 es
layout(location = 1) in ivec4 aCell;

gl.GetInteger(GetPName.MajorVersion, out int major);
if (major < 3) throw new InvalidOperationException("Integer-attribute linking requires GL/ES 3.0+ (WebGL2).");

try { return CreateProgram(gl, vert, frag); }
catch (Exception ex) { Log.Error($"IntAttribs link failed: {ex.Message}"); throw; }

When it happens

Trigger: Vertex shader declares integer attributes (`in ivec4`) under a GLSL version that doesn't support them; varying interface mismatch between stages; `layout(location=)` collision; fragment shader reading an integer varying as float; GLSL version below 300 es rejecting integer attributes.

Common situations: Sample running on WebGL1/ES2 lacking integer attributes and instancing; refactor that changed a varying type in only one stage; driver link bug for integer varyings.

Related errors

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

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/fd52f95444658b87. Report an issue: GitHub.