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= 2.12.1 (2019-08-06)

This release contains bugfixes and minor enhancements.

This release improves the performance of capturing location information, makes `log4j-core` optional in the log4j 1.2 bridge, and explicitly removes `LoggerContext` references from components that keep track of them when the LoggerContext is shut down.
More details on the new features and fixes are itemized below.

Due to a break in compatibility in the SLF4J binding, Log4j now ships with two versions of the SLF4J to Log4j adapters.
`log4j-slf4j-impl` should be used with SLF4J 1.7.x and earlier and `log4j-slf4j18-impl` should be used with SLF4J 1.8.x and later.

Note that the XML, JSON and YAML formats changed in the 2.11.0 release: they no longer have the `timeMillis` attribute and instead have an `Instant` element with `epochSecond` and `nanoOfSecond` attributes.

The Log4j 2.12.1 API, as well as many core components, maintains binary compatibility with previous releases.

Log4j 2.12.1 requires a minimum of Java 8 to build and run.
Log4j 2.3 was the last release that supported Java 6 and Log4j 2.11.2 is the last release to support Java 7.

Basic compatibility with Log4j 1.x is provided through the `log4j-1.2-api` component, however it does
not implement some of the very implementation specific classes and methods.
The package names and Maven `groupId` have been changed to `org.apache.logging.log4j` to avoid any conflicts with Log4j 1.x.

For complete information on Apache Log4j 2, including instructions on how to submit bug reports, patches, or suggestions for improvement, see http://logging.apache.org/log4j/2.x/[the Apache Log4j 2 website].


[#release-notes-2-12-1-changed]
=== Changed

* Make Log4j Core optional for Log4j 1.2 API. (https://issues.apache.org/jira/browse/LOG4J2-2556[LOG4J2-2556])
* Update MongoDB 3 driver from 3.10.1 to 3.10.2. (https://issues.apache.org/jira/browse/LOG4J2-2646[LOG4J2-2646])
* Improve exception messages in the JDBC appender. (https://issues.apache.org/jira/browse/LOG4J2-2657[LOG4J2-2657])
* Retry when JDBC throws a java.sql.SQLTransactionRollbackException in commitAndClose(). (https://issues.apache.org/jira/browse/LOG4J2-2660[LOG4J2-2660])

[#release-notes-2-12-1-fixed]
=== Fixed

* Allow file renames to work when files are missing from the sequence. (https://issues.apache.org/jira/browse/LOG4J2-1946[LOG4J2-1946])
* Remove references to LoggerContext when it is shutdown. (https://issues.apache.org/jira/browse/LOG4J2-2366[LOG4J2-2366])
* Improve the performance of capturing location information. (https://issues.apache.org/jira/browse/LOG4J2-2644[LOG4J2-2644])
* Support emulating a MAC address when using ipv6. (https://issues.apache.org/jira/browse/LOG4J2-2650[LOG4J2-2650])
* AbstractAction.reportException records a warning to the status logger, providing more information when file based appenders fail to compress rolled data asynchronously. (https://issues.apache.org/jira/browse/LOG4J2-2658[LOG4J2-2658])
* AbstractAction handles and records unchecked RuntimeException and Error in addition to IOException. (https://issues.apache.org/jira/browse/LOG4J2-2659[LOG4J2-2659])
* "Values not bound to statement" when using JDBC appender, appender does not respect bufferSize="0". (https://issues.apache.org/jira/browse/LOG4J2-2667[LOG4J2-2667])
