Give a mod author a bug report they can use

A useful crash report starts with the last thing you tried to do. “The game closed while leaving a world” and “the game closed when opening a chest” point to different situations. Record that action before changing files or launching again.

The goal is to give someone a short route to the problem, with the right evidence attached. You do not have to identify the broken line of code yourself.

Keep the report from the right run

Open the folder of the Java instance that failed. Check crash-reports for a file whose timestamp matches the event. Also copy logs/latest.log somewhere separate before another launch replaces it. A failed launch may leave a log without producing a crash report.

When you use several launcher instances, open the folder from the affected instance. A recent report from another modpack is still the wrong report. Keep the original files intact while you read copies.

Start with the stage of the failure

Here is a short excerpt from an actual report produced in our Java 26.2 session:

Time: 2026-09-28 07:26:23
Description: Client shutdown from post-main
java.lang.Error: Watchdog (Client shutdown from post-main)

The description places this event during client shutdown. That is useful context to include in a report. These three lines do not establish which mod caused it, whether a world was damaged, or which setting would fix it. Naming a mod from somewhere farther down the stack trace would require more evidence than this excerpt provides.

Use the rest of the file to record the environment: game version, loader and listed mods. In this example, the report identifies Minecraft 26.2 and Fabric Loader 0.19.5. Those belong in the report alongside the action, rather than being replaced by “the newest version.”

Write steps another player can follow

Use a short numbered sequence. A storage interaction might be described as: open a fresh test world, place the named block, put one named item inside, close its screen, then reopen it. That is an example of useful wording, not a claim that this happened in the shutdown report above.

Keep these points together:

• Exact Minecraft, loader, mod and required-library versions.
• The world or server situation: a new save, one older save, or every world.
• The action immediately before the failure.
• What should have happened, what happened instead, and whether repeating the same steps produced the same result.

If the launcher names a missing dependency, address that named requirement first. If several content mods are involved, use a disposable test instance and keep required libraries together while narrowing the combination. Do not remove a content mod and reopen your only valuable save to experiment.

Share enough evidence, without private details

Read the copied log before uploading it. Redact private server addresses, personal paths or authentication data when present, and say what you removed. Preserve the surrounding error context and the full remaining text; a screenshot of the last line is difficult to search and can hide the earlier exception.

Start with Report on the project page

Sign in, return to the project's page here and choose Report a problem in its side panel. For a download issue, first open the Files tab and note the release name and exact filename. The report belongs to the project, so those details identify which file you mean.

1. In What is the problem?, choose Incorrect compatibility or requirements when the published game version or dependencies are wrong. For a crash that does not establish a compatibility error, choose Another problem.
2. In Help us understand, enter the release, filename, Minecraft version and loader, followed by the action, result and short steps. There is no separate version selector: type those details into this field.
3. Include the relevant error excerpt within the 3,000-character limit. This form has no file-attachment control, so keep your complete report and log available separately. Remove private details before sharing any excerpt.
4. Review what you wrote, choose Send report, then follow the moderation response in My reports. Reporting does not automatically hide the project.

The empty form shows where to report a problem; it has not been submitted. If the author also provides an issue tracker, that is an additional route for a detailed technical investigation, rather than a requirement for reporting a problem here. When a later trial works, record the exact file or setting that changed.