Launching Bugs
What to check first when the game crashes on start or mid-game, where the crash report is, and what to send us.
Check these first
- Your own mods. The most common crash by far is a mod made for another version or loader. Every mod in a 1.21.11 profile must be for Fabric 1.21.11. On the Profiles page, switch off every mod you added yourself and try again. If it starts, turn them back on one at a time to find the one at fault.
- Run on Java 25. If you switched it on, switch it off on the Profiles page and try again.
- Graphics drivers. Update them from your GPU maker (NVIDIA, AMD or Intel), not through Windows Update. Old drivers are behind a lot of crashes on start and almost every Iris shader crash.
- Memory. On the Profiles page, set memory to 4 to 6 GB. Too little crashes when the game runs out; far too much can starve Windows on an 8 GB PC.
- Damaged files. Turn on Verify files on launch and Repair corrupted files on launch in Settings, then launch again.
On 1.21.11, Crash Recovery catches most crashes while you play: it saves the crash report, leaves the world or server, and keeps the game open instead of closing it. A second crash within 30 seconds, or a crash while the game is loading, still closes it.
Finding the crash report
Each profile has its own folder inside %USERPROFILE%\SourClientData\instances, named after the profile (spaces become underscores). In it:
| File | What it is |
|---|---|
crash-reports\crash-….txt | Minecraft's crash report, written when the game itself catches the crash. |
logs\latest.log | The full log of the last run. The end of it usually says what went wrong. |
hs_err_pid….log | Only when Java itself crashed, usually a graphics driver. |
The launcher's own logs are in %USERPROFILE%\SourClientData\logs: launcher.log, and one file per launch in launches.
Turn on Show game log console in Settings to watch the log live in a window beside the game.
Sending it to us
Open a ticket on the support page with the crash report or latest.log attached, your version and profile, and what you were doing. How to write a good bug report.