Crash Reporting for Games With Custom Engines

Off-the-shelf engines ship a crash reporter you can switch on. A custom engine ships nothing, which means the safety net is whatever you build, and most teams discover this the first time a player sends a vague report about the game closing itself. The flip side is that you control the entire engine, so you can capture context no generic reporter could reach: your scene graph state, your job system queues, your allocator stats. This post covers building the handler, walking and symbolizing the stack, and deciding which engine internals to attach so a single crash report points straight at the failing subsystem.

No framework means no safety net

When you write your own engine, you own the failure path too. There is no parent runtime to catch an access violation and pop a dialog; if you do not install a handler, the process simply dies and the player sees nothing useful. This is not a reason to avoid custom engines, it is a reason to treat crash handling as a core engine subsystem rather than a feature you bolt on later. The teams that ship custom engines well build the crash path early and exercise it constantly.

The benefit hiding inside this responsibility is reach. A generic crash reporter sees registers and a stack; your engine sees the frame number, the active scene, the asset that was streaming, the size of every allocator pool, and the state of your task scheduler. Because you wrote all of it, you can capture precisely the state that explains the crash. The work is in deciding what to collect and doing it safely inside a process that is already falling over.

Building the fatal-fault handler

Install a handler for the platform faults you care about: structured exceptions on Windows, signals like SIGSEGV and SIGABRT on Unix-like systems. Inside it, assume nothing about the heap, because the allocator may be the thing that broke. Use a preallocated buffer, avoid calling back into your own systems that might fault again, and keep the handler small. Its only jobs are to capture the machine state, walk the stack into raw frames, and write a compact record you can analyze later.

Resist the urge to do clever recovery in the handler. The process is unstable, so the safest design captures the minimum and then either writes a file or hands the record to a tiny separate reporter process that survives the crash. Many robust setups fork a watcher or use an out-of-process reporter precisely so the part that uploads the report is not running inside the corrupted address space. Get the capture solid and dumb first; sophistication can come once you trust it.

Walking and symbolizing the stack yourself

A raw stack walk gives you return addresses and module offsets. Turning those into function names and source lines is symbolization, and on a custom engine you own both ends. Build with debug information, split the symbols into separate files keyed by a build identifier, and archive them. At crash time you only need to record the module base addresses and the offsets; resolving them against the archived symbols happens offline, on a machine that is not on fire, using the symbol file that matches the build the player ran.

Generate a minidump or your own equivalent so you can load the crash in a debugger after the fact. The combination of a minidump and the matching symbols lets you inspect locals and walk the heap as it was at the moment of the fault, which is far more powerful than a flat trace. Key everything to the build identifier so an old report still resolves cleanly, and never ship the symbols to players; they stay in your archive next to the build that produced them.

Attaching the context only your engine knows

This is where a custom engine pays you back. Maintain a small ring buffer of recent significant events: the last assets loaded, the last few state transitions, the current frame index, the active subsystem. Keep it in preallocated memory so the handler can read it without touching the broken heap. When a crash fires, that breadcrumb trail often tells you more than the trace, because it shows what the engine was doing in the seconds before the fault, not just where the program counter landed.

Snapshot the cheap-to-read internals that explain whole classes of crashes: allocator high-water marks, pool exhaustion flags, the depth of your job queues, the current resolution and graphics backend. An out-of-memory crash and a use-after-free both land in the allocator, but pool stats tell them apart at a glance. Decide this list deliberately, capture it safely, and every report becomes a snapshot of your engine's health rather than an anonymous address.

Setting it up with Bugnet

Bugnet gives you the reporting layer so you can focus on capture rather than infrastructure. Your handler produces a stack trace and a bundle of engine context; Bugnet stores it with device and platform details and presents it in one dashboard. Map your engine internals to custom fields, the active scene, the failing subsystem, the allocator state, and they become searchable and filterable instead of buried in a blob. The in-game report button also captures game state automatically, so a tester filing a non-fatal glitch carries the same context a hard crash would.

Occurrence grouping matters on a custom engine because your bugs cluster around the subsystems you are actively building. Folding identical crashes into one counted issue tells you which of your own systems is costing you the most, and filtering by the subsystem custom field points you straight at the code to open. Instead of a pile of raw dumps, you get a ranked list of your engine's weak spots, which is exactly the prioritization a small team writing its own engine needs to ship.

Treat the crash path as a real subsystem

The mistake is treating crash handling as a one-time setup. On a custom engine it is a living subsystem that has to keep pace with the rest of the code, so when you add a new allocator or a new job system, you extend the crash context to cover it. Budget time for this the way you budget time for rendering or audio. A crash reporter that knew your engine two years ago but not today will mislead you exactly when you most need it.

Exercise the whole chain on a schedule. Trigger a fault deliberately, confirm the report arrives, pull the matching symbols, and verify the trace and context resolve correctly on every platform you ship. A custom engine gives you unmatched insight into your own crashes, but only if the capture, symbol, and reporting paths all work together. Keep them tested and tied to your build, and your home-grown engine ends up easier to debug in production than many off-the-shelf ones.

A custom engine has no safety net but total visibility. Build the crash path as a real subsystem and capture the internals only you can reach.