# Ilverify Failure

> Fix ILVerify baseline failures when IL shape changes (codegen, new types, method signatures). Use when CI fails on ILVerify job.

- Skill: `dotnet/ilverify-failure` (Agent Skill)
- Install (CLI): `npx skillmds@latest add dotnet/ilverify-failure`
- Raw SKILL.md: https://api.skillmd.com/api/skills/dotnet/ilverify-failure/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: .NET (Microsoft) (https://skillmd.com/u/dotnet)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/dotnet/ilverify-failure

---


# ILVerify Baseline

## When to Use
IL shape changed (codegen, new types, method signatures) and ILVerify CI job fails.

## Offset-Only Differences
Changes that only shift IL byte offsets (`[offset 0x...]`) — for example adding code above an existing error site — are detected automatically and **do not fail CI**. A warning is printed suggesting a baseline update. No action is required, but refreshing baselines keeps them accurate.

## Update Baselines
```bash
TEST_UPDATE_BSL=1 pwsh tests/ILVerify/ilverify.ps1
```
Or use the `/run ilverify` PR comment command to update baselines via CI.

## Baselines Location
`tests/ILVerify/*.bsl`

## Verify
Re-run without `TEST_UPDATE_BSL=1`, should pass.