Numeric fields have been refactored to use a different data structure that performs better for range queries. However, since this data structure does not record document frequencies, numeric fields need to fall back to running queries in order to estimate the number of matching documents in the background set, which may incur a performance degradation.

It is recommended to use keyword fields instead, either directly or through a multi-field if the numeric representation is still needed for sorting, range queries or numeric aggregations like stats aggregations.

Now that Elasticsearch supports ipv6, ip addresses are encoded in the index using a binary representation rather than a numeric representation. As a consequence, the output of ip_range aggregations does not give numeric values for from and to anymore.

size: 0 is no longer valid for the terms, significant terms and geohash grid aggregations. Instead a size should be explicitly specified with a number greater than zero.

Fractional time values (e.g., 0.5s) are no longer supported. For example, this means when setting date histogram intervals "1.5h" will be rejected and should instead be input as "90m".