SearchStax Help Center

The SearchStax Help Center Frequently Asked Questions page includes FAQs about SearchStax Managed Search, our hosted Apache Solr Cloud service.

510 Not Extended Error

In SearchStax, a 510 Error is usually accompanied by a message saying, “No active replicas found for collection.” It occurs at the end of a cascade of updates or queries that fill up JVM and run the system out of memory.

Look for solr_oom_killer log files on the servers. Each log represents a moment when the server ran out of memory and restarted itself.

Common Causes of 510 Errors

  • Expensive updates: New users sometimes overload Solr indexing by demanding a commit after every add (commit=true) or within a second of every add (commitWithin=1000). Frequent commits are expensive and can overload the system to the point of putting replicas into recovery mode. See Timeouts during ingestion: Too many commits!
  • Expensive queries: Another way to cause a gateway timeout is to send Solr a stream of expensive queries. New users often request a million response-items (rows=1000000) when ten would do. Queries using “deep pagination” can take a long time to complete. Logically complex queries (with many AND/OR clauses) can also be very slow. See Solr Out of Memory (OOM): Causes and Solutions.


Do not hesitate to contact the SearchStax Support Desk.

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