The Log4j 1.2 Bridge allows applications coded to use Log4j 1.2 API to use Log4j 2 instead.
The Log4j 1.2 bridge is dependent on the Log4j 2 API and implementation. For more information, see Runtime Dependencies.
To use the Log4j Legacy Bridge just remove all the Log4j 1.x jars from the application and replace them with the bridge jar. Once in place all logging that uses Log4j 1.x will be routed to Log4j 2. However, applications that attempt to modify legacy Log4j by adding Appenders, Filters, etc may experience problems if they try to verify the success of these actions as these methods are largely no-ops.