Errors and recovery

Symptom	Likely cause	Action	Index usable?
No hits	Field, analyser or query does not match indexed terms	Check field type and use the same analyser at index and query time	Yes
Locked files on Windows	Reader, writer or output remains open	Dispose the owner and retry after lifecycle cleanup	Usually
Slow search	Broad query, cold file cache or excessive candidate window	Measure the workload, inspect metrics and reduce work deliberately	Yes
Merge pressure	Indexing outpaces background merge capacity	Reduce ingestion pressure or review merge and storage settings	Yes
Corrupt index	Missing or invalid files	Run the checker, recover a valid commit or restore a backup	Not until recovered

See Validation and recovery and Production deployment.