I noticed slight differences in the Solr version for Sitecore 9 update 1. Here 6.6.1 is mentioned whereas the installation guide has 6.6.2. Does the initial 9 release need 6.6.1 and update 1 requires 6.6.2?

1 Answer 1


Do not use SOLR 6.6.1 due to a Solr Bug that has been identified.

Use SOLR 6.6.2, which is the recommended version. The KB article has not been updated to reflect this except in footnote:

Solr server can try to initialize a Solr core twice, resulting in the following error:

> org.apache.solr.common.SolrException: Unable to create core
> [core_name] ... Caused by:
> org.apache.lucene.store.LockObtainFailedException: Lock held by this
> virtual machine:
> C:\solr-6.6.1\server\solr\core_name\data\index\write.lock The error is
> caused by a Solr bug: SOLR-11297

The issue does not affect Sitecore functionality and can be ignored. To resolve the issue, upgrade Solr to 6.6.2.

  • Is there anything written in the Sitecore specs about getting the recommended Solr version to a non dead version or LTS version?
    – Bakudan
    Commented Sep 5, 2019 at 11:40
  • Nothing written in docs. Lots of folks have had no problem using the LTS version. Commented Sep 5, 2019 at 23:08

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