The upgrade that quietly changes your search results
Solr 7 and 8 are past community end of life. Moving to 9 means a full reindex and a Java baseline change -- and a relevance profile nobody budgeted for revalidating.
Challenge
A Solr major upgrade is not a version bump. Solr 9 requires a reindex, raises the Java baseline, and can shift relevance scoring in ways that only show up as worse search results, days later, reported by users rather than by tests.
Environment
Solr 7.x or 8.x serving production search, with a relevance configuration tuned over years and no reindex rehearsal.
Approach
OSSeva patches the running Solr line so the upgrade stops being a security deadline, then plans the reindex and relevance validation as its own scoped piece of work.
What this delivers
CVE coverage now, and a Solr 9 move that gets validated against the relevance profile before it reaches users.