| name | binlog-failure-analysis |
| description | Analyze MSBuild binary logs to diagnose build failures. USE FOR: unclear MSBuild errors, cascading failures across multi-project builds, tracing target execution/order, and inspecting evaluated properties/items. Requires an existing .binlog or explicit permission to generate one. DO NOT USE FOR: non-MSBuild build systems. |
| license | MIT |
Analyzing MSBuild Failures with Binary Logs
This skill diagnoses MSBuild failures from .binlog evidence.
Repository integration: a binlog MCP server is optional, not assumed. Use it only when the current agent environment exposes one. Otherwise use MSBuild's built-in binary-log replay path. Do not attempt to read a .binlog as plain text.
Preferred path — structured binlog tooling when available
If a binlog-aware MCP/tool is available, use it to inspect:
- errors and warnings;
- MSBuild properties and final values;
- items such as
PackageReference and ProjectReference;
- project evaluation data;
- target execution details;
- embedded project/source contents when supported.
Synthesize findings as evidence accumulates. Do not keep exploring after the cause and affected target/property chain are sufficiently established.
Fallback — replay binary log to focused text logs
dotnet msbuild build.binlog -noconlog \
-fl -flp:v=diag;logfile=full.log;performancesummary \
-fl1 -flp1:errorsonly;logfile=errors.log \
-fl2 -flp2:warningsonly;logfile=warnings.log
PowerShell requires appropriate quoting around semicolon-delimited logger parameters.
Then search the generated text logs rather than the binary file itself:
cat errors.log
grep -n -B2 -A2 "CS0246" full.log
grep -i "CoreCompile.*FAILED\|Build FAILED\|error MSB" full.log
Generating a binlog when needed
If no binlog exists and the task requires one:
dotnet build /bl:build.binlog
Prefer the narrowest failing project/command that reproduces the issue. Treat the generated binlog and replay logs as temporary diagnostic artifacts unless the user explicitly asks to retain them.
Validation
