{"slug":"android-tombstone-symbolication","title":"android-tombstone-symbolication","summary":"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 tr","platform":"Claude","tags":[],"authorName":"LLM Mart","authorSlug":"llm-mart","score":0,"source":"github","price":null,"verified":false,"createdAt":"2026-08-24T05:37:25.719906Z","repo":{"url":"https://github.com/dotnet/skills","stars":5471,"forks":418,"license":"MIT","updatedAt":"2026-09-24T06:38:55Z"},"bodyHtml":"
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name: android-tombstone-symbolication\ndescription: 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.\nlicense: MIT

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Android Tombstone .NET Symbolication

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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.

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

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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.

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Workflow

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Step 1: Parse the Tombstone Backtrace

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Each backtrace frame has this format:

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#NN pc OFFSET  /path/to/library.so (optional_symbol+0xNN) (BuildId: HEXSTRING)\n
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Extract: frame number, PC offset (hex, already library-relative), library name, and BuildId (32–40 hex chars).

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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.

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Format notes:

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Step 2: Identify .NET Runtime Libraries

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Filter frames to .NET runtime libraries:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
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)
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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.

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

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Step 3: Download Debug Symbols

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For each unique .NET BuildId, download debug symbols:

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

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Step 4: Symbolicate Each Frame

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llvm-symbolizer --obj=libmonosgen-2.0.so.debug -f -C 0x222098\n
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Output:

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ves_icall_System_Environment_FailFast\n/__w/1/s/src/runtime/src/mono/mono/metadata/icall.c:6244\n
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The /__w/1/s/ prefix is the CI workspace root — the meaningful path starts at src/runtime/, mapping to dotnet/dotnet VMR.

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Step 5: Present the Symbolicated Backtrace

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

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#00  libc.so              abort+164\n#01  libmonosgen-2.0.so   ves_icall_System_Environment_FailFast        (mono/metadata/icall.c:6244)\n#02  libmonosgen-2.0.so   do_icall                                     (mono/mini/interp.c:2457)\n#03  libmonosgen-2.0.so   mono_interp_exec_method                      (mono/mini/interp.c)\n
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For unresolved frames (??), keep the original line with BuildId and PC offset.

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Automation Script

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

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pwsh scripts/Symbolicate-Tombstone.ps1 -TombstoneFile tombstone_01.txt -LlvmSymbolizer llvm-symbolizer\n
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Flags: -CrashingThreadOnly (limit to crashing thread), -OutputFile path (write to file), -ParseOnly (report libraries/BuildIds/URLs without downloading), -SkipVersionLookup (skip runtime version identification).

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Finding llvm-symbolizer

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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.

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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.

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Understanding the Output

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CI source paths use these prefixes:

\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
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
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Runtime Version Identification

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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).

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Validation

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

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Common Pitfalls

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