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Official agent skill

Android Tombstone Symbolication

by dotnet in dotnet/skills

Resolves native crash frames from .NET Android tombstones to function names, source files and line numbers using BuildIds, Microsoft's symbol server and llvm-symbolizer.

OfficialMITAuto-check passedMobile

Install Android Tombstone Symbolication

skills CLI
$ npx skills add dotnet/skills --skill android-tombstone-symbolication -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install dotnet/skills android-tombstone-symbolication --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/dotnet/skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/dotnet-diag/skills/android-tombstone-symbolication .claude/skills/android-tombstone-symbolication && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
android-tombstone-symbolication
GitHub stars
5.6k
Used in
1 other repo
Token cost
~2.1k tokens
SKILL.md length
785 words
Files
2 (incl. scripts)
Skills in repo
91
Repo updated
First seen
Licence
MIT

At a glance

Resolves native crash frames from .NET Android tombstones to function names, source files and line numbers using BuildIds, Microsoft's symbol server and llvm-symbolizer.

  • Works in 5 steps: Parse the Tombstone Backtrace → Identify .NET Runtime Libraries → Download Debug Symbols → …
  • Triaging a .NET MAUI or Mono Android app crash from a tombstone
  • SKILL.md covers Workflow, Finding llvm-symbolizer, Understanding the Output and Validation, plus 2 more sections
  • Runs PowerShell scripts from its folder; calls adb, curl and pwsh; reaches msdl.microsoft.com

What it does

The skill takes a tombstone file or logcat crash output, extracts each backtrace frame's number, library-relative PC offset, library name and BuildId, and symbolicates all threads by default because background threads often hold useful .NET frames. A bundled PowerShell script, Symbolicate-Tombstone.ps1, detects frame lines with or without a backtrace header and strips logcat prefixes; if parsing fails, the agent falls back to manual extraction.

It filters to .NET runtime libraries (libmonosgen-2.0.so for Mono, libcoreclr.so for CoreCLR and the libSystem native components), skips Android system libraries unless asked, and notes that NativeAOT apps link the runtime into the app binary and need the app's own symbols. Logcat tombstones often lack BuildIds, which can be recovered with readelf over adb, CI artifacts or the runtime NuGet package. It is not for managed exceptions, pure Java or Kotlin crashes, or iOS logs.

When your agent uses it

  • Triaging a .NET MAUI or Mono Android app crash from a tombstone
  • Resolving frames in libmonosgen-2.0.so or libcoreclr.so to runtime source
  • Investigating SIGABRT or SIGSEGV signals that come from the .NET runtime on Android

Example prompts

  • “Symbolicate the .NET frames in ./crashes/tombstone.txt from our MAUI app.”
  • “This logcat output has a SIGSEGV in libcoreclr.so; resolve the frames to source lines.”
  • “The tombstone has no BuildIds. How can we recover them?”

Requirements

  • PowerShell to run Symbolicate-Tombstone.ps1
  • llvm-symbolizer from the Android NDK or an LLVM 14+ toolchain
  • Internet access to download symbols

Workflow steps

5 steps, taken from the step headings in SKILL.md.

  1. Parse the Tombstone Backtrace
  2. Identify .NET Runtime Libraries
  3. Download Debug Symbols
  4. Symbolicate Each Frame
  5. Present the Symbolicated Backtrace

What it can do on your machine

Read from SKILL.md and the folder at commit a660de8. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Ships 1 file in scripts/ (PowerShell), which the agent can run.

    Shell commands in SKILL.md call:

    • adb
    • curl
    • pwsh
    • brew
    • apt
    • xcrun

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    Hosts in commands or code, which the agent is likely to contact:

    • msdl.microsoft.com

    Also links to:

    • github.com

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Android Tombstone Symbolication loads about 2.1k tokens when it runs. Until then it costs about 197 tokens; SKILL.md has 785 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~197
When it runs · the whole SKILL.md, loaded when a task matches
~2.1k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); the scripts in this folder are not scanned.

SKILL.md

The full file from dotnet/skills at commit a660de8, republished under its MIT licence (© dotnet). 785 words, ~2,051 tokens.

Download SKILL.mdSave it as .claude/skills/android-tombstone-symbolication/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.
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.
  • GitHub issue pastes may mangle #1 pc into issue links — replace org/repo#N pc with #N pc before saving to a file.
  • If the script fails to parse a format, fall back to manual extraction of #NN pc OFFSET library.so (BuildId: HEX) tuples.
Step 2: Identify .NET Runtime Libraries

Filter frames to .NET runtime libraries:

LibraryRuntime
libmonosgen-2.0.soMono (MAUI, Xamarin, interpreter)
libcoreclr.soCoreCLR (JIT mode)
libSystem.*.so.NET BCL native components (Native, Globalization.Native, IO.Compression.Native, Security.Cryptography.Native.OpenSsl, Net.Security.Native)

NativeAOT: No libcoreclr.so or libmonosgen-2.0.so — the runtime is statically linked into the app binary (e.g., libMyApp.so). The libSystem.*.so BCL libraries remain separate and can be symbolicated via the symbol server. For the app binary itself, you need the app's own debug symbols.

Skip libc.so, libart.so, and other Android system libraries unless the user specifically asks.

Step 3: Download Debug Symbols

For each unique .NET BuildId, download debug symbols:

https://msdl.microsoft.com/download/symbols/_.debug/elf-buildid-sym-<BUILDID>/_.debug
bash
curl -sL "https://msdl.microsoft.com/download/symbols/_.debug/elf-buildid-sym-1eb39fc72918c7c6c0c610b79eb3d3d47b2f81be/_.debug" \
  -o libmonosgen-2.0.so.debug

Verify with file libmonosgen-2.0.so.debug — should show ELF 64-bit ... with debug_info, not stripped. If the download returns 404 or HTML, symbols are not published for that build. Do not add or subtract library base addresses — offsets in tombstones are already library-relative.

Step 4: Symbolicate Each Frame
bash
llvm-symbolizer --obj=libmonosgen-2.0.so.debug -f -C 0x222098

Output:

ves_icall_System_Environment_FailFast
/__w/1/s/src/runtime/src/mono/mono/metadata/icall.c:6244

The /__w/1/s/ prefix is the CI workspace root — the meaningful path starts at src/runtime/, mapping to dotnet/dotnet VMR.

Step 5: Present the Symbolicated Backtrace

Combine original frame numbers with resolved function names and source locations:

#00  libc.so              abort+164
#01  libmonosgen-2.0.so   ves_icall_System_Environment_FailFast        (mono/metadata/icall.c:6244)
#02  libmonosgen-2.0.so   do_icall                                     (mono/mini/interp.c:2457)
#03  libmonosgen-2.0.so   mono_interp_exec_method                      (mono/mini/interp.c)

For unresolved frames (??), keep the original line with BuildId and PC offset.

Automation Script

scripts/Symbolicate-Tombstone.ps1 automates the full workflow:

powershell
pwsh scripts/Symbolicate-Tombstone.ps1 -TombstoneFile tombstone_01.txt -LlvmSymbolizer llvm-symbolizer

Flags: -CrashingThreadOnly (limit to crashing thread), -OutputFile path (write to file), -ParseOnly (report libraries/BuildIds/URLs without downloading), -SkipVersionLookup (skip runtime version identification).

Finding llvm-symbolizer

Check the Android NDK first: $ANDROID_NDK_ROOT/toolchains/llvm/prebuilt/*/bin/llvm-symbolizer or $ANDROID_HOME/ndk/*/toolchains/llvm/prebuilt/*/bin/llvm-symbolizer. Also available via brew install llvm, apt install llvm, or xcrun --find llvm-symbolizer on macOS.

If unavailable, complete steps 1–3 and present the download commands and llvm-symbolizer commands for the user to run. Do not spend time installing LLVM.

Show full SKILL.md (290 more words)Show less

Understanding the Output

CI source paths use these prefixes:

Path prefixMaps to
/__w/1/s/src/runtime/src/runtime/ in dotnet/dotnet VMR
/__w/1/s/src/mono/src/mono/ in the VMR (older builds)
/__w/1/s/VMR root
Runtime Version Identification

The script identifies the exact .NET runtime version by matching BuildIds against locally-installed runtime packs. It searches: SDK packs ($DOTNET_ROOT/packs/), NuGet cache (~/.nuget/packages/), and NuGet.org as an online fallback. When found, it extracts the version and source commit from the .nuspec <repository commit="..." /> element. Pass -SkipVersionLookup to disable. Requires llvm-readelf (auto-discovered from the NDK).

Validation

  1. file <debug-file> shows ELF ... with debug_info, not stripped
  2. At least one .NET frame resolves to a function name (not ??)
  3. Resolved paths contain recognizable .NET runtime structure (e.g., mono/metadata/, mono/mini/)

Stop Signals

  • No .NET frames found: Report parsed frames and stop.
  • All frames resolved: Present symbolicated backtrace. Do not trace into source or attempt to build/debug the runtime.
  • Symbols not available (404): One attempt per BuildId, then stop. Report unsymbolicated frames with BuildIds and offsets.
  • llvm-symbolizer not available: Use -ParseOnly, present manual commands. Do not install LLVM.

Common Pitfalls

  • Missing BuildIds: Logcat tombstones often omit BuildIds. Recover via: adb shell readelf -n /path/to/lib.so, CI build artifacts, or the runtime NuGet package (~/.dotnet/packs/Microsoft.NETCore.App.Runtime.Mono.android-arm64/<version>/). Prefer pulling raw tombstone files (adb shell cat /data/tombstones/tombstone_XX) which always include BuildIds.
  • Symbols not found (404): Pre-release/internal builds may not publish symbols. Check for local unstripped .so/.so.dbg in build artifacts or the NuGet runtime pack.
  • NativeAOT: No runtime .so in the tombstone — runtime is in the app binary. libSystem.*.so BCL libraries still work with the symbol server; the app binary needs its own debug symbols.
  • Wrong llvm-symbolizer version: Use LLVM 14+ for best DWARF compatibility.
  • Multiple BuildIds: Each .NET library has its own BuildId — download symbols for each separately.

© dotnet, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 1 other file (scripts) in plugins/dotnet-diag/skills/android-tombstone-symbolication of dotnet/skills.

  • SKILL.md
  • scripts/Symbolicate-Tombstone.ps1

Open the folder on GitHubat commit a660de8

Used in 1 other repository

We found 2 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in dotnet/skills, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Android Tombstone Symbolication next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

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Maui AI DebuggingRedth/Maui.Gtk101—~4.1kAutomated safety check: PassMIT
Inspect Network TrafficHedvigInsurance/android154—~756Automated safety check: PassAGPL-3.0

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Works with

Categories

Questions about Android Tombstone Symbolication

What does Android Tombstone Symbolication do?

Resolves native crash frames from .NET Android tombstones to function names, source files and line numbers using BuildIds, Microsoft's symbol server and llvm-symbolizer. NET frames.ps1, detects frame lines with or without a backtrace header and strips logcat prefixes; if parsing fails, the agent falls back to manual extraction.

When should I use Android Tombstone Symbolication?

Android Tombstone Symbolication fits situations like: triaging a .NET MAUI or Mono Android app crash from a tombstone; resolving frames in libmonosgen-2.0.so or libcoreclr.so to runtime source; investigating SIGABRT or SIGSEGV signals that come from the .NET runtime on Android.

How do I install Android Tombstone Symbolication in Claude Code?

Run `npx skills add dotnet/skills --skill android-tombstone-symbolication -a claude-code`. Or copy the skill folder (plugins/dotnet-diag/skills/android-tombstone-symbolication in dotnet/skills) into .claude/skills/android-tombstone-symbolication in your project. Claude Code loads it when a task matches its description.

How do I install Android Tombstone Symbolication in Codex?

Run `npx skills add dotnet/skills --skill android-tombstone-symbolication -a codex`. Or copy the skill folder (plugins/dotnet-diag/skills/android-tombstone-symbolication in dotnet/skills) into .agents/skills/android-tombstone-symbolication in your project. Codex loads it when a task matches its description.

Can I use Android Tombstone Symbolication in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add dotnet/skills --skill android-tombstone-symbolication -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/android-tombstone-symbolication, .gemini/skills/android-tombstone-symbolication, .github/skills/android-tombstone-symbolication and .opencode/skills/android-tombstone-symbolication in your project.

What does Android Tombstone Symbolication need to run?

Going by SKILL.md and its folder, Android Tombstone Symbolication needs PowerShell for the scripts in its folder and the command-line tools its instructions call (adb, curl, pwsh, brew, apt and xcrun). Our summary lists: PowerShell to run Symbolicate-Tombstone.ps1; llvm-symbolizer from the Android NDK or an LLVM 14+ toolchain; Internet access to download symbols.

Does Android Tombstone Symbolication access the network?

SKILL.md names 2 domains. In commands or code: msdl.microsoft.com; the agent is likely to contact it when it follows the instructions. As links in the text: github.com. This is read from the text; nothing was executed.

Is Android Tombstone Symbolication safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. The check reads SKILL.md only: the scripts in the folder are not scanned, so read them before running anything.

What licence does Android Tombstone Symbolication use?

Android Tombstone Symbolication is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Android Tombstone Symbolication use?

About 2.1k tokens (SKILL.md is roughly 8.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Android Tombstone Symbolication?

Skills that share tags, products or a category with Android Tombstone Symbolication: Android Debugging (rcosteira79/android-skills, 151 stars), Android Hidden API and R8 Check (gkd-kit/gkd, 43k stars), Coding Style (sk2andy/candy-browser, 488 stars) and Maui AI Debugging (Redth/Maui.Gtk, 101 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Android Tombstone Symbolication?

dotnet (a GitHub organization, an official publisher) maintains it in dotnet/skills, which has 5,576 GitHub stars. The repository holds 91 skills in this directory. The repository was last updated on October 8, 2026.

Source: dotnet/skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.