When upgrading from a previous release you are advised to clear down the journal files and persistent database first before upgrading to this jar as the binary format of messages is not compatible with 3.x or earlier 4.0 milestone releases.
Some folks have found issues with acknowledgements, particularly when using auto-ack mode. This has been fixed in 4.0.1 which will be released shortly. Until then we recommend you disable optimizeAcknowledge. e.g. connect via
The source distributions do not build as is anymore due to changes in the way the maven repo is now setup at Apache. You must first apply the following patch before doing the build. You will need to download the patch and apply it using the patch command.
The 4.x branch of Apache ActiveMQ has now moved to the Apache Incubator so the package names have changed from org.activemq to org.apache.activemq. For a full list see the Changes in 4.0.
For a more detailed view of new features and bug fixes, see the release notes
jiraissues: Unable to determine if sort should be enabled.
Also see the previous ActiveMQ 4.0 RC2 Release