build-failure-analysis

name	build-failure-analysis
description	Investigate MSBuild build failures using binlog-insights MCP tools. Use when a dotnet build or msbuild command fails, NuGet restore fails, or you see errors like CS0246, NU1101, MSB3644, MSB4019. Also triggers for missing type, missing package, import not found, and SDK resolution issues.
metadata	{"traits":"MSBuild|DotNet|CSharp|NuGet|Build|Binlog"}

Build Failure Analysis

Overview

Diagnose MSBuild build failures by analyzing .binlog files. Drills from high-level build status down to specific root causes using binlog-insights MCP tools.

Quick Start

dotnet build /bl:build.binlog

Then ask: "My build failed. Investigate build.binlog and tell me what went wrong."

Workflow

1. Run binlog_overview to check build status, duration, and project count
2. Run binlog_errors to get all errors with project, file, line, and target context
3. Drill deeper based on error type:
   • CS0246 / CS0234 (missing type or namespace) → binlog_items with type PackageReference to check if the dependency exists. Check binlog_properties for TargetFramework to rule out TFM mismatch
   • NU1101 / NU1102 / NU1103 (NuGet resolution failure) → binlog_nuget for restore diagnostics and feed configuration
   • MSB3644 / MSB3270 (reference assembly not found) → binlog_compiler for reference paths, binlog_imports for SDK resolution
   • MSB4019 / MSB4057 (missing import or target) → binlog_imports to trace the import chain
   • Other errors → binlog_search with the error code or key terms
4. If needed, use binlog_preprocess to see the fully expanded project XML after all imports
5. Summarize: what failed, why, and what needs to change

Task Progress:
- [ ] Step 1: binlog_overview — get build status
- [ ] Step 2: binlog_errors — get all errors
- [ ] Step 3: Drill into each error type
- [ ] Step 4: Summarize root cause and fix

Tool Reference

Tool	Purpose
binlog_overview	Build status, duration, project count
binlog_errors	Errors with project, file, line context
binlog_warnings	Warnings with context
binlog_properties	MSBuild property values (use --filter)
binlog_items	Item groups: PackageReference, Compile, etc.
binlog_imports	Full import chain for a project
binlog_nuget	NuGet restore diagnostics and feed issues
binlog_compiler	Full compiler command line
binlog_search	Free-text search across all messages
binlog_preprocess	Effective project XML after all imports

Common Patterns

Missing NuGet package: Error: NU1101: Unable to find package 'Foo.Bar' Action: binlog_nuget → check feed configuration → verify package name and source

Missing type after upgrade: Error: CS0246: The type or namespace name 'JsonConvert' could not be found Action: binlog_items --type PackageReference --project MyApp → verify Newtonsoft.Json is referenced → check binlog_properties --filter TargetFramework

Missing import: Error: MSB4019: The imported project "...\Microsoft.Cpp.Default.props" was not found Action: binlog_imports --project MyApp → trace the import chain → check SDK installation

Troubleshooting

• No binlog file: Rebuild with dotnet build /bl:build.binlog
• Tool not found: Ensure binlog-insights-mcp is installed: dotnet tool install -g BinlogInsights.Mcp
• Large result sets: Use --limit and --offset for pagination
• Filter to one project: Use --project <substring> on any tool to narrow results