Solr Upgrade Notes

The following notes describe changes to Solr in recent releases that you should be aware of before upgrading.

These notes highlight the important changes that may impact the largest number of implementations. It is not a comprehensive list of all changes to Solr in any release.

When planning your Solr upgrade, consider the customizations to your system and review the CHANGES.txt file found in your Solr package. That file includes all the changes and updates that may affect your existing implementation.

Detailed steps for upgrading a Solr cluster are in the section Upgrading a Solr Cluster.

Zookeeper Credentials support now follows a new paradigm. Old classes, such as VMParamsAllAndReadonlyDigestZkACLProvider and VMParamsSingleSetCredentialsDigestZkCredentialsProvider, are deprecated but still supported until at least 10.0. Users are encouraged to upgrade to the non-deprecated classes before the next major version release. Please refer to deployment-guide:zookeeper-access-control.adoc#solr-to-zookeeper-acls-workflow for more information.

Upgrading to 9.0 from 8.x Releases

The upgrade from 8.x to Solr 9.0 introduces several major changes that you should be aware of before upgrading. These changes are described in the section Major Changes in Solr 9. It’s strongly recommended that you thoroughly review that section before starting your upgrade.

If you run in SolrCloud mode and use SolrJ’s CloudSolrClient, you must first upgrade SolrJ to a version 8.10 or higher before upgrading the cluster to 9.0.
Rolling upgrades from Solr 8 to Solr 9 require first upgrading the cluster to version 8.7 or newer.

Upgrading from Pre-8.x Versions

Users upgrading from versions prior to 8.x are strongly encouraged to consult CHANGES.txt for the details of all changes since the version they are upgrading from.

The upgrade from 7.x to 8.0 introduced several major changes that you should be aware of before upgrading. Please do a thorough review of the section Major Changes in Solr 8 before starting your upgrade.

A summary of the significant changes between Solr 6.x and Solr 7.0 is in the section Major Changes in Solr 7.