cPanel Dovecot Solr search does not work after the update to version 9.8+

Symptoms

New versions of cPanel Dovecot Solr (cpanel_dovecot_solr) show the following error in the logs:

[root@server ~]# less /home/cpanelsolr/server/logs/solr.log
...
2025-07-04 11:35:25.922 ERROR (coreLoadExecutor-14-thread-1) [c: s: r: x:dovecot t:] o.a.s.s.CacheConfig Error instantiating cache => org.apache.solr.common.SolrException:  Error loading class 'solr.search.LRUCache'
        at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:553)
org.apache.solr.common.SolrException:  Error loading class 'solr.search.LRUCache'
        at org.apache.solr.core.SolrResourceLoader.findClass(SolrResourceLoader.java:553) ~[?:?]
...

Description

Legacy cache configurations LRUCache, LFUCache and FastLRUCache are deprecated and removed in Solr 9.0

We've opened an internal case for our development team to investigate this further. For reference, the case number is CPANEL-48106. Follow this article to receive an email notification when a solution is published in the product. 

Workaround

Update the cache method in the configuration file.

sed -i.solrconfig_8.xml -e 's/solr.*LRUCache/solr.CaffeineCache/g' /home/cpanelsolr/server/solr/dovecot/conf/solrconfig.xml

Rebuild the cache.

/usr/local/cpanel/3rdparty/scripts/cpanel_dovecot_solr_rebuild_index