Upgrade Notes:

• Upgrading from 0.19 requires a full cluster restart.

Breaking Changes:

• Shared Gateway has been deprecated (2459)
• Snappy compression has been deprecated (2458)
• Plugins Installer: Allow to download plugins from download.elasticsearch.org (#2507)
• Sometimes MapperParsingException and sometimes not (#2354)

Enhancements:

• Support filter inside has_parent and has_child filter (#2588)
• Make script cache configurable and bounded (#2539)

Bug fixes:

• Primary shard failure with initializing replica shards can cause the replica shard to cause allocation failures (#2592)
• Parent & child queries can fail if a segment doesn’t have documents with the targeted type or associated parent type (#2537)
• NullPointerException during parent/child query (ES 0.20.2) (#2536)
• Update request with upsert may fail. (#2530)