Package net.neoforged.neoforge.event

Class ModMismatchEvent

java.lang.Object

net.neoforged.bus.api.Event

net.neoforged.neoforge.event.ModMismatchEvent

All Implemented Interfaces:

net.neoforged.fml.event.IModBusEvent

public class ModMismatchEvent
extends net.neoforged.bus.api.Event
implements net.neoforged.fml.event.IModBusEvent

Fires when the mod loader is in the process of loading a world that was last saved with mod versions that differ from the currently-loaded versions. This can be used to enqueue work to run at a later point, such as multi-file migration of data.

Note that level and world information has not yet been fully loaded; as such, it is unsafe to access server or level information during handling of this event.

This event is not cancellable, and does not have a result.

This event is fired on the mod-specific event bus, on both logical sides.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final record	ModMismatchEvent.MismatchedVersionInfo
static final record	ModMismatchEvent.MismatchResolutionResult

Nested classes/interfaces inherited from class net.neoforged.bus.api.Event

net.neoforged.bus.api.Event.HasResult, net.neoforged.bus.api.Event.Result

Field Summary

Fields

Modifier and Type	Field	Description
private final LevelStorageSource.LevelDirectory	levelDirectory	The level being loaded.
private final HashMap<String,net.neoforged.fml.ModContainer>	resolved	Which mods have specified that they have handled version mismatches.
private final HashMap<String,ModMismatchEvent.MismatchedVersionInfo>	versionDifferences	A set of previously-known versions that have mismatched with the currently loaded versions.

Constructor Summary

Constructors

Constructor	Description
ModMismatchEvent(LevelStorageSource.LevelDirectory levelDirectory, Map<String,org.apache.maven.artifact.versioning.ArtifactVersion> previousVersions, Map<String,org.apache.maven.artifact.versioning.ArtifactVersion> missingVersions)

Method Summary

Modifier and Type	Method	Description
boolean	anyResolved()
boolean	anyUnresolved()
@Nullable org.apache.maven.artifact.versioning.ArtifactVersion	getCurrentVersion(String modid)
LevelStorageSource.LevelDirectory	getLevelDirectory()	Gets the current level directory for the world being loaded.
@Nullable org.apache.maven.artifact.versioning.ArtifactVersion	getPreviousVersion(String modId)	Fetch a previous version of a given mod, if it has been mismatched.
Stream<ModMismatchEvent.MismatchResolutionResult>	getResolved()
Optional<net.neoforged.fml.ModContainer>	getResolver(String modid)
Stream<ModMismatchEvent.MismatchResolutionResult>	getUnresolved()
Optional<ModMismatchEvent.MismatchedVersionInfo>	getVersionDifference(String modid)
void	markResolved(String modId)	Marks the mod version mismatch as having been resolved safely by the current mod.
boolean	wasResolved(String modId)	Fetches the status of a mod mismatch handling state.

Methods inherited from class net.neoforged.bus.api.Event

getResult, hasResult, setResult

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

levelDirectory

private final LevelStorageSource.LevelDirectory levelDirectory

The level being loaded. Useful for things like DimensionDataStorage to manage multiple files changing between mod versions.

versionDifferences

private final HashMap<String,ModMismatchEvent.MismatchedVersionInfo> versionDifferences

A set of previously-known versions that have mismatched with the currently loaded versions.

resolved

private final HashMap<String,net.neoforged.fml.ModContainer> resolved

Which mods have specified that they have handled version mismatches.

Constructor Details

ModMismatchEvent

@Internal
public ModMismatchEvent(LevelStorageSource.LevelDirectory levelDirectory,
 Map<String,org.apache.maven.artifact.versioning.ArtifactVersion> previousVersions,
 Map<String,org.apache.maven.artifact.versioning.ArtifactVersion> missingVersions)

Method Details

getLevelDirectory

public LevelStorageSource.LevelDirectory getLevelDirectory()

Gets the current level directory for the world being loaded. Can be used for file operations and manual modification of mod files before world load.

getPreviousVersion

@Nullable
public @Nullable org.apache.maven.artifact.versioning.ArtifactVersion getPreviousVersion(String modId)

Fetch a previous version of a given mod, if it has been mismatched.

Parameters:

modId - The mod to fetch previous version for.

Returns:

The previously known mod version, or Optional.empty() if unknown/not found.

getCurrentVersion

@Nullable
public @Nullable org.apache.maven.artifact.versioning.ArtifactVersion getCurrentVersion(String modid)

markResolved

public void markResolved(String modId)

Marks the mod version mismatch as having been resolved safely by the current mod.

wasResolved

public boolean wasResolved(String modId)

Fetches the status of a mod mismatch handling state.

getVersionDifference

public Optional<ModMismatchEvent.MismatchedVersionInfo> getVersionDifference(String modid)

getResolver

public Optional<net.neoforged.fml.ModContainer> getResolver(String modid)

anyUnresolved

public boolean anyUnresolved()

getUnresolved

public Stream<ModMismatchEvent.MismatchResolutionResult> getUnresolved()

anyResolved

public boolean anyResolved()

getResolved

public Stream<ModMismatchEvent.MismatchResolutionResult> getResolved()