Apache Log4j Files

This minor release introduces bug fixes, behavior improvements, and complete support for GraalVM native image generation.

GraalVM Reachability Metadata

Log4j Core and all extension modules now include embedded
GraalVM reachability metadata,
enabling seamless generation of native images with GraalVM out of the box—no manual configuration required.
For more information, refer to our GraalVM guide.

[!NOTE]
When building third-party Log4j plugins, using the new GraalVmProcessor
introduced in version 2.25.0 will automatically generate the required reachability metadata for GraalVM native images.
However, the processor will fail the build if the required log4j.graalvm.groupId and log4j.graalvm.artifactId parameters are not provided.
For detailed instructions, see Registering plugins.

Exception Handling in Pattern Layout

Exception handling in Pattern Layout has undergone a significant rewrite.
This update resolves several bugs and ensures consistent behavior across all exception converters.
Key improvements include:

• Stack traces are now consistently prefixed with a newline instead of other whitespace.
• The default exception converter has changed from extended to plain, offering better performance.
• Support for the {ansi} option in exception converters has been removed.

Date & Time Formatting

Log4j has historically provided custom date and time formatters for performance, such as FixedDateFormat and FastDateFormat.
These are now deprecated in favor of Java’s standard DateTimeFormatter.

If you encounter formatting issues after upgrading—particularly with n or x directives—you can temporarily revert to the legacy formatters by setting the log4j2.instantFormatter property to legacy.
Please report any issues via our issue tracker.

ANSI Support on Windows

Modern Windows versions (10 and newer) provide native ANSI escape sequence support.
As a result, dependency on the outdated JAnsi 1.x library has been removed.
For details, refer to ANSI styling on Windows.

Jakarta JMS Appender

A Jakarta-compatible version of the JMS Appender is now included in the core distribution.

Added

• Add Google OSS-Fuzz integration (#2949)
• Add a GraalVmProcessor annotation processor to generate GraalVM reachability metadata. (#3053)
• Add MonitorResource configuration option to support the monitoring of external files in addition to the configuration file itself. (#3074, [#3501])
• Fixed typo in "LoggerConfig.RootLogger.Builder#withtFilter(...)" method. Created new corrected 'withFilter()' method and deprecated old method. (#3369)
• Add collectionName and databaseName arguments to the MongoDB appender (#3467)

Changed

• Remove JAnsi library support. Windows 10 console has supported ANSI escapes since 2017. (#1736)
• Consolidate exception rendering logic and improve circular reference support in Pattern Layout (#2691, [#3123])
• Rewrite JAnsiTextRenderer to work without JAnsi library. (#2916)
• Switch prefixing stack traces in Pattern Layout from whitespace to newline (#3045)
• Changes the layout used by the default configuration. (#3118)
• Switch to using Java's DateTimeFormatter for date & time formatting of log event instants (#3121, [#2943])
• Switch the default exception converter from the extended exception converter to the plain exception converter (#3123)
• Don't close StringReaders because of batching. (#3127)
• Switch prefixing stack traces in Status Logger from whitespace to newline (#3149)
• The MongoDb Appender shouldn't log a deprecation warning (#3149)
• Add improved validation to StringMatchFilter for null/empty text. (#3153)
• Improve sub-millisecond precision in Java 8 by overriding SystemClock. (#3217)
• Don't overwrite configured configuration name if config has no loggers/root logger. (#3431)
• Update GcpLayout.json to improve compatibility with Google Cloud Logging (#3586)
• Direct invocation of java.util.Base64 in Base64Util instead of reflection (#3686)
• Improve LogEvent.toImmutable(), ReusableMessage.memento(), and remove ThrowableProxy usage

Deprecated

• ThrowableProxy and all its usages (#2691, [#3123])
• AbstractLogger.checkMessageFactory() (#2936)
• FixedDateTime, FastDateTime, and supporting classes (#3121)
• Use hard references to Loggers in LoggerRegistry. (#3143)

Fixed

• Switch MongoDB tests to Docker (#2229)
• Add Jakarta-based JMS Appender and deprecate Javax version (#2995)
• Fix RollingFileManager to reopen file on unsuccessful rollover (#2592)
• Fix exception rendering in Pattern Layout (LOG4J2-2170, LOG4J2-3627, [#1729], [#2691])
• Reload key/trust stores in TLS config (LOG4J2-2988, [#2767])
• Simplify SSLContext instantiation for TLS (#2767)
• Add warning for Plugin Builder Attributes without public setter (#2769)
• Fix config reload from HTTP(S) source (#2937)
• Fix putAll() in thread context map (#2942)
• Improve HTTP Appender validation (#3011)
• Fix getLogger() compatibility in log4j-1.2-api (#3030)
• Fix root exception property extraction in Pattern Layout (#3045)
• Fix key removal in Thread Context (#3048)
• Android-specific fixes (#3056)
• Prevent non-Log4j dependency leak in log4j-bom (#3066, logging-parent#265)
• Fix o.a.l.Priority to Log4j 2 Level conversion (#3085)
• Sync Logger.getLevel() and Logger.setLevel() (#3119)
• Improve AsyncWaitStrategyFactoryConfig validation (#3159)
• Fix NPE with rootLogger = LEVEL syntax (#3206)
• Fix ArrayIndexOutOfBoundsException in JSON Template Layout (#3212)
• Handle null replacement in RegexReplacement (#3215)
• Fix location requirement detection in AsyncAppender and FailoverAppender (#3257)
• Correct Javadoc return for isFiltered() (#3300)
• Fix Level converter documentation (#3359)
• Fix RecyclerFactoryConverter loading in JSON Layout (#3398)
• Minimize InternalLoggerRegistry locking and clean up stale entries (#3399, [#3430], [#3681])
• Improve compile-time visibility for annotation libraries (#3437)
• Fix shutdownDisable config (#2614)
• Fix ArrayIndexOutOfBoundsException in StatusData#getFormattedStatus (#3562)
• Deprecate/remove static hiding methods (#3601)
• Avoid stack poisoning on platforms without SecurityManager (#3639)
• Improve performance/memory use when logging primitive arrays (#3645)
• Fix ArrayIndexOutOfBoundsException in Message.getFormattedMessage() (#3655)
• StatusLogger now writes to stderr by default (fixes regression in 2.23.0) (#3665)
• Support equals() between ReadOnlyStringMap implementations (#3669)
• Accept Disruptor 4 in OSGi descriptor (#3706)
• Avoid surrogate handling in JsonWriter

Removed

• Removed support for the {ansi} option in Pattern Layout exception converters (#3045)

Updated

• Update actions/stale to 9.1.0 (#3625)
• Update logback-core to 1.3.15 (#3354)
• Update jackson-bom to 2.19.0 (#3708)
• Update spotbugs-annotations to 4.9.3 (#3545)
• Update docker-maven-plugin to 0.46.0 (#3592)
• Update cassandra-all to 3.11.19 (#3440)
• Update commons-csv to 1.14.0 (#3559)
• Update commons-dbcp2 to 2.13.0 (#3271)
• Update commons-pool2 to 2.12.1 (#3422)
• Update kafka-clients to 3.9.1 (#3678)
• Update logging-parent to 12.1.1
• Update tomcat-juli to 10.1.30 (#2999)
• Update jetty-util to 9.4.57.v20241219 (#3377)
• Update jmdns to 3.6.1 (#3544)
• Update bson to 5.5.1 (#3722)
• Update slf4j-api to 2.0.17 (#3499)
• Update spring-cloud-context to 4.3.0 (#3700)