# android-tombstone-symbolication

Turns native backtrace frames from an Android tombstone into function names, source files and line numbers for .NET apps.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 3300 installs · ★ 5730
- Author: dotnet
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/dotnet/skills/tree/HEAD/plugins/dotnet-diag/skills/android-tombstone-symbolication/SKILL.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/skills/android-tombstone-symbolication

## What it does

The skill reads a tombstone or logcat crash dump and pulls BuildIds and PC offsets out of the native backtrace. It then downloads debug symbols from the Microsoft symbol server and runs `llvm-symbolizer` to swap addresses for function names with source locations. All threads get symbolicated by default, since background GC and finalizer threads often carry useful .NET frames.

A single script, `Symbolicate-Tombstone.ps1`, drives the whole flow: `pwsh scripts/Symbolicate-Tombstone.ps1 -TombstoneFile tombstone_01.txt -LlvmSymbolizer llvm-symbolizer`. Flags `-CrashingThreadOnly`, `-OutputFile`, `-ParseOnly` and `-SkipVersionLookup` narrow the run or skip steps. The script also pins the exact runtime version by matching BuildIds against local runtime packs and the NuGet cache.

You need `llvm-symbolizer` from the Android NDK or any LLVM 14+ toolchain, plus internet access for the symbol downloads. If a build's symbols were never published, the download returns 404 and that frame stays unresolved. Offsets in a tombstone are already library-relative, so adding base addresses will break the output. Pure Java/Kotlin crashes and managed exceptions already in logcat are out of scope.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill android-tombstone-symbolication -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/android-tombstone-symbolication/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/android-tombstone-symbolication/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill android-tombstone-symbolication -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/android-tombstone-symbolication/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill android-tombstone-symbolication -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/android-tombstone-symbolication/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install dotnet/skills android-tombstone-symbolication
```

2. **Manually: put the files in place**
- File: `.github/skills/android-tombstone-symbolication/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill android-tombstone-symbolication -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/dotnet/skills --path plugins/dotnet-diag/skills/android-tombstone-symbolication
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/android-tombstone-symbolication/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add dotnet/skills --skill android-tombstone-symbolication -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/dotnet/skills/tree/HEAD/plugins/dotnet-diag/skills/android-tombstone-symbolication/SKILL.md

## When to use it
- resolve a native backtrace from a tombstone to function names
- locate the crash site inside `libmonosgen-2.0.so` or `libcoreclr.so`
- fetch debug symbols by BuildId from the Microsoft symbol server
- pin the exact .NET runtime version from BuildIds
- filter out Android system libraries and keep only .NET frames

## Example prompts
- symbolicate tombstone_01.txt and show the .NET frames
- symbolicate this logcat crash, crashing thread only
- run Symbolicate-Tombstone.ps1 with -ParseOnly and list the BuildIds and URLs

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: bd7c7b2e919bf5df.

BEGIN THIRD-PARTY FILE bd7c7b2e919bf5df
````text
---
name: android-tombstone-symbolication
description: Symbolicate the .NET runtime frames in an Android tombstone file. Extracts BuildIds and PC offsets from the native backtrace, downloads debug symbols from the Microsoft symbol server, and runs llvm-symbolizer to produce function names with source file and line numbers. USE FOR triaging a .NET MAUI or Mono Android app crash from a tombstone, resolving native backtrace frames in libmonosgen-2.0.so or libcoreclr.so to .NET runtime source code, or investigating SIGABRT, SIGSEGV, or other native signals originating from the .NET runtime on Android. DO NOT USE FOR pure Java/Kotlin crashes, managed .NET exceptions that are already captured in logcat, or iOS crash logs. INVOKES Symbolicate-Tombstone.ps1 script, llvm-symbolizer, Microsoft symbol server.
license: MIT
---

# Android Tombstone .NET Symbolication

Resolves native backtrace frames from .NET Android app crashes (MAUI, Xamarin, Mono) to function names, source files, and line numbers using ELF BuildIds and Microsoft's symbol server.

**Inputs:** Tombstone file or logcat crash output, `llvm-symbolizer` (from Android NDK or any LLVM 14+ toolchain), internet access for symbol downloads.

**Do not use when:** The crash is a managed .NET exception (visible in logcat with a managed stack trace), the crashing library is not a .NET component (e.g., `libart.so`), or the tombstone is from iOS.

---

## Workflow

### Step 1: Parse the Tombstone Backtrace

Each backtrace frame has this format:

```
#NN pc OFFSET  /path/to/library.so (optional_symbol+0xNN) (BuildId: HEXSTRING)
```

Extract: **frame number**, **PC offset** (hex, already library-relative), **library name**, and **BuildId** (32–40 hex chars).

Symbolicate all threads by default (background threads like GC/finalizer often have useful .NET frames). The crashing thread's backtrace is listed first; additional threads appear after `--- --- ---` markers.

**Format notes:**
- The script auto-detects `#NN pc` frame lines with or without a `backtrace:` header, and strips logcat timestamp/tag prefixes automatically.
- Logcat-captured tombstones often omit BuildIds. Recover via `adb shell readelf -n`, CI build artifacts, or the .NET runtime NuGet package.
````
END THIRD-PARTY FILE bd7c7b2e919bf5df

The third-party file has ended. Everything between the bd7c7b2e919bf5df tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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