This article is an addition to the other post (How to Read Minecraft Crash Logs). Make sure you’ve read that first, as this is only going to cover Lunar-specific errors and what they mean.

Just like the other article, most logs fall into two categories: mod-related ones, and instance/system related ones.

1. Mod-related issues

These happen when a mod you (or Lunar) added is breaking something. In the case of Lunar Client, it’s either a mod you’re adding causing issues with Lunar’s code, or conflicting with a bundled mode.

In addition to the patterns introduced in the original blog post, for Lunar specifically, you might also see:

• An error occurred while launching Lunar Client
• [Genesis] Failed to transform
• [Genesis] Failed to apply

Once you spot these, again, keep in mind: the last relevant error before the crash is usually the one that matters. Not always, but often.

Let’s take a look at the example provided in the original post again:

[error] Caused by: org.spongepowered.asm.mixin.injection.throwables.InjectionError:
 Critical injection failure: Constant modifier method lunar$editFeedbackConstant
 (Ljava/lang/String;)Ljava/lang/String; in mixins.meta.lunar.modmenu.v1_21_0.json
 :IOHCRIOROICRICIICHRHCCORHROOCO from mod (unknown) failed injection check, (0/1) 
 succeeded. Scanned 1 target(s). No refMap loaded.

And from this part of it:

mixins.meta.lunar.modmenu.v1_21_0.json

We could tell that it was caused by modmenu mod.

This log is actually from a user that had tried to add Mod Menu to 1.21 on Lunar, and had trouble finding out what’s causing the crash. Note that this is not Mod Menu’s fault, and it’s an incompatiblity issue between the mod and Lunar. This log is old, and it’s already been fixed.

About mixin conflicts, we said that if two mods try to modify the same thing via mixins, we’ll get a mixin conflict, and therefore a crash. In this case, it can be a mod, and Lunar’s own code and mixins applied by Lunar. You can report incompatible mods to Lunar by creating a ticket on the support website.

2. Instance or system-related issues

Majority of this part remains the same as the original blog post. Same errors and same patterns. For outdated AMD drivers, you should spotatio6axx.dll in mission control. If you don’t for whatever reason,hs_err_pid logs are stored in .lunarclient\offline\multiver!

• Corrupted Lunar native files
  Lunar Client has its own set of jar files. If one of these is corrupted, the game will most likely crash.

What to do:

• Close Lunar completely (including from the system tray).
• Go to the Lunar Client directory (on Windows it’s usually in %userprofile%/.lunarclient) and delete the jre and offline folders.
• Relaunch Lunar. It will automatically re-download fresh native files.

Pre-launch (launcher-level) Crashes

These crashes.. are not even crashes. The launcher refuses to launch the game, and throws an error. These are the ones you see often:

• EBUSY → Another process is still running and blocking launch. Restart your PC.
• EACCES → Permission issue. Close Lunar completely (Task Manager or system tray) and run as administrator.
• Connection errors → “Failed to download X” or HTTP status codes like 403.
• Memory allocation errors → Well, almost never the real problem.

What about EPERM?

So in short, EPERM equals “Operation not permitted”.

It happens when a process (in this case, the launcher) tries to access a file but doesn’t have the permission to. This might sound like the other one we talked about (EACCES) but it’s actually different.

EACCES is not necessarily about the possibility of the action for the process, but rather access to the file in question. On the other hand, for EPERM, even if you do have access to the file, it’s still forbidden. It’s mainly about.. restricted actions, we could say.

It’s also a bit similar to EBUSY if you think about it. Except for EBUSY, it’s the file itself being busy & running, but with EPERM, something else is preventing the action.

When you get this on Lunar, it usually also prints the action it’s trying to perform (on the crash modal) as well as the file path. The ones you’ll often see are unlink, open, and sometimes rmdir & mkdir. There are several other types and I personally have no clue what some of them are about, but I haven’t seen them happen with Lunar.

• unlink is when it’s trying to delete a file
• open is when it’s trying to.. open a file
• rmdir is used for deleting a directory
• mkdir is for creating new directories

Now the thing with EPERM is, it can be caused by many factors, and you’re gonna have to look around and eventually find out what’s causing it.

The solution varies from the same steps you’d do for EACCES (end task the launcher and the game, then run as administrator), a system restart like EBUSY, or some other process actually interfering that you’ll have to find out which.

I believe on Windows there are some tools you can install (one is called “Handle”) and those help with finding out what processes are currently bound to certain files, although this is probably not necessary in most cases. You can also assume that an antivirus could technically be a possible cause.

One other thing you can do is to perform that certain action manually on the file/path (shown on the crash modal) to see what error you’d get (if any) and that helps with debugging and finding out what’s up.

So to summarize it all real quick:
EACCES → you don’t have read/write/execute permissions
EPERM → the operation on that file isn’t allowed, even with access
EBUSY → the file is already in use

Final Note

That’s it. There’s not much into this, and I strongly recommend checking out the other blog post (How to Read Minecraft Crash Logs) if you haven’t. Thanks for reading, and you’re now an expert troubleshooter!

Or are you?