Crash reports#
Every once in a while, rbx will crash on you: not a report error, but an actual traceback, the kind that means rbx itself has a bug.
When that happens, the traceback, the command you ran, and
the directory you ran it in are useful pieces to debug, but are always in the worst possible place: your terminal
scrollback. By the time you get around to looking into it, you've scrolled past it, or closed the
window, and all you remember is that "something broke during rbx build".
So rbx writes it down. After a crash, you'll see a line like this:
Crash report written to /Users/you/Library/Application Support/rbx/crashes/20260905T094952Z-86725.md
That file has everything the terminal had.
What's in it#
The report is a Markdown file that opens with a block of context and then shows the full traceback:
---
rbx_version: "1.4.2"
timestamp: "2026-09-05T09:49:52.248804+00:00"
command: "rbx build"
cwd: "/Users/you/contest/problem-a"
package: "/Users/you/contest/problem-a"
exception: "RuntimeError"
message: "synthetic crash"
python: "3.14.3"
platform: "darwin"
pid: 86725
argv: ["rbx", "build"]
---
# rbx crash
`rbx build` in `/Users/you/contest/problem-a`
## Traceback
...
Where to find it#
Reports live in the crashes folder of your rbx app directory: ~/Library/Application
Support/rbx on MacOS, ~/.config/rbx on Linux. Only the newest 20 are kept, since old crashes
stop being interesting once the bug behind them is fixed. A latest.md symlink beside them always
points at the most recent one:
<app dir>/crashes/
├── 20260905T094952Z-86725.md
├── 20260904T171203Z-47110.md
└── latest.md -> 20260905T094952Z-86725.md
If the crash happened inside a problem or contest package, you'll also find a last-crash.md
symlink inside that package's .rbx cache folder, pointing at the same report. It's just a
shortcut for finding the crash that belongs to the package you're working on. It's a cache
folder, so the shortcut disappears whenever the cache is cleared.