high severityApache Solr vector search (DenseVectorField)
In SolrCloud multi-shard collections, DenseVectorField data appears as list of strings (e.g., [\"0.1\", \"0.2\"]) instead of floats ([0.1, 0.2]) when retrieved via Admin UI or queries. KNN vector queries fail or return incorrect results. Works fine in single-shard or standalone mode.
Root cause
In multi-shard SolrCloud mode prior to the fix, DenseVectorField serialized stored vectors as strings instead of native float arrays during distributed response assembly, breaking KNN queries that expect numeric vectors.
DenseVectorFieldknn_vectorSolrCloudmulti-shardserializationSOLR-16952