ExceptionFinder for Reflector: Rapidly Locate Runtime Errors in .NET Assemblies

From Stack Trace to Source: ExceptionFinder for Reflector WorkflowWhen an application fails in production, the stack trace is often the only artifact you get. It can point you to the failing method, but rarely gives you the full context needed to fix the bug quickly — obfuscated assemblies, missing PDBs, or optimized builds make mapping a stack trace to actual source lines difficult. ExceptionFinder for Reflector is a tool designed to bridge that gap: it helps you convert stack traces into meaningful navigation through compiled .NET assemblies inside Reflector so you can find the root cause faster.

This article explains the complete workflow: how to prepare your environment, import and analyze stack traces, use ExceptionFinder features to locate the forcing code, and practical tips to verify and fix the issue. It assumes familiarity with .NET debugging basics and Reflector (Redgate’s .NET Reflector or comparable decompilers that support add-ins).

Why stack traces alone are often insufficient

A stack trace shows the call chain at failure time, but:

• Missing PDBs or mismatched PDBs mean line numbers and file names are absent.
• Obfuscated assemblies replace identifiers, making method names meaningless.
• Inlined or optimized code can change call shapes, hiding the true source.
• Third-party libraries often come only as compiled binaries without accessible source.

ExceptionFinder aims to work within those constraints by matching stack trace entries to decompiled methods, offering heuristics and UI tools to speed mapping from exception text to code.

What ExceptionFinder for Reflector does (core features)

• Stack trace parsing: Automatically recognize .NET stack trace lines and extract assembly, type, and method tokens.
• Assembly resolution: Locates the corresponding assembly files in your project output, symbol paths, NuGet packages, or a configured assembly cache.
• Method matching: Matches stack trace entries to decompiled methods in Reflector, even when signatures differ due to compiler optimizations.
• Heuristic ranking: Ranks candidate methods when multiple matches exist, based on name similarity, parameter types, and IL pattern matches.
• Navigation and context: Opens matched methods in Reflector’s decompiler view, shows surrounding methods/callers, and highlights likely exception sources.
• Integration with PDBs and source servers: When symbols and source information are available, ExceptionFinder will prefer precise mapping and show file/line links.
• Batch processing: Process multiple stack traces at once, useful for error-reporting logs or aggregated crash dumps.

Environment setup: prerequisites and recommended configuration

1. Install Reflector and the ExceptionFinder add-in compatible with your Reflector version.
2. Have access to the application’s compiled assemblies (bin folder, deployment package, or symbol server) and PDBs if available.
3. Configure search paths inside ExceptionFinder:
   • Local build outputs (Debug/Release folders)
   • Symbol servers (if you use a private or Microsoft symbol server)
   • NuGet package cache (for third-party assemblies)
   • Fallback folder for archived builds
4. If source servers or SourceLink are used, configure the tool to fetch source files for precise file/line mapping.
5. Optionally, set up an assembly-identity mapping file if your deployed assembly names have been renamed or repackaged.

Step-by-step workflow

1. Collect the stack trace(s)

   • From logs, error-reporting systems, user reports, or crash dump analysis.
   • Prefer full stack traces including inner exceptions. If available, include exception types and messages.

2. Paste or import stack traces into ExceptionFinder

   • The parser will highlight recognized lines and parse tokens (assembly, type, method, plus file/line if present).

3. Resolve assemblies

   • ExceptionFinder attempts to locate the assembly referenced by each stack entry using configured search paths.
   • If an assembly cannot be found automatically, you can point ExceptionFinder to a matching DLL or ZIP containing the build.

4. Match methods

   • The tool lists candidate decompiled methods for each stack frame.
   • Candidates are ranked; top matches show a confidence score. Select the candidate to navigate the decompiled code in Reflector.

5. Inspect IL and decompiled source

   • View both the decompiled C# (or VB) and the IL to confirm correctness.
   • IL inspection is crucial when optimizations or obfuscation are suspected — it reveals compiler-generated patterns and inlining artifacts.

6. Trace callers and context

   • Use Reflector to explore callers, callee relationships, and the broader class context.
   • ExceptionFinder can highlight likely exception-throwing instructions (throw, newobj of Exception types, array index checks, etc.).

7. Validate with PDBs or source mapping

   • If PDBs are available, ExceptionFinder will show precise file and line numbers and offer source navigation.
   • With SourceLink/source servers, fetch the original source file to confirm the exact code path.

8. Reproduce and fix

   • Once the suspect method and code path are identified, reproduce the issue locally if possible.
   • Apply the fix, add defensive checks or better error handling, and update tests or monitoring to catch regressions.

Handling common complications

• Obfuscated code: rely on IL patterns and cross-check call sites. ExceptionFinder’s heuristics help but cannot fully recover original identifiers.
• Missing assemblies: search deployment artifacts, package caches, or request the exact build from the release process.
• Mismatched PDBs: prefer the PDB that matches the assembly’s timestamp and public token. If unavailable, use IL-level analysis.
• Inlined/optimized methods: examine caller IL and look for compiler-generated state machines (async/await, iterator methods) which relocate logic.

Practical tips to speed triage

• Always capture full exception text including inner exceptions and any custom data.
• Keep a build artifact archive with both DLLs and matching PDBs — it dramatically reduces mapping time.
• Use a symbol server in your CI/CD pipeline so production builds can be resolved post-deployment.
• Enable SourceLink for open-source or internal shared libraries to allow precise source mapping from PDBs.
• Triage high-volume exceptions first — ExceptionFinder’s batch mode can mark frequently occurring stack traces for priority.

Example: quick walkthrough (concise)

1. Paste stack trace: “System.NullReferenceException: Object reference not set to an instance of an object at MyApp.Services.UserService.GetUser(String id) in :line 0”
2. ExceptionFinder parses frame, locates MyApp.Services.dll in the Release folder.
3. Top candidate method shown; open decompiled C# and IL.
4. IL shows a call to a property that can return null; decompiled view reveals missing null-check.
5. Confirm with PDB — file and line available; implement null-guard and add unit tests.

When to use ExceptionFinder vs. full dump debugging

Use ExceptionFinder when you have stack traces (textual) from logs and need rapid mapping to source inside Reflector. If you have full crash dumps with process memory, native frames, or the need to inspect runtime state (heap, threads), consider a native debugger or WinDbg alongside managed debugging extensions. ExceptionFinder complements dump analysis by accelerating identification of the suspect methods.

Security and privacy considerations

Be cautious when decompiling third-party or licensed assemblies — ensure you have rights to inspect them. When sharing stack traces or assemblies for help, strip sensitive data and avoid leaking tokens, keys, or personal information.

Conclusion

ExceptionFinder for Reflector turns noisy stack traces into actionable navigation inside decompiled assemblies, saving time during production triage. Its combination of parsing, assembly resolution, heuristic matching, and source/PDB integration helps you go from an exception text to the exact suspect code quickly — especially when PDBs or source links are available. Properly configured (symbol servers, archived builds, SourceLink), it becomes a force-multiplier for on-call engineers and debugging teams.