*Details:* Kibana 6.0.0 and onward only support 64 bit operating systems.
*Impact:* You will need to install Kibana 6.x on a 64 bit operating system. No extra data migration steps are necessary when moving from 32 bit to 64 bit.
*Details:* Setting the NODE_ENV environment variable can break Kibana processes in unexpected ways, which is especially unfortunate since it is a common environment variable to have configured on a system, and you wouldn't expect it to break anything in Kibana. Kibana will now effectively ignore NODE_ENV entirely.
*Impact:* If you're developing a custom plugin that depends on NODE_ENV, you will need to update it to use a different, custom environment variable.
=== Kibana 4.x configuration names using `_` instead of `.` have been removed
*Details:* In Kibana 4.2, we renamed all configuration names in kibana.yml to use `.` as a separator instead of `_`, though the legacy configurations would still continue to work. In 5.0, we started logging deprecation notices whenever the legacy configurations were encountered. In 6.0 onward, legacy configuration names that use an underscore instead of a dot will no longer work.
*Impact:* Any usages of underscore separated configuration names in kibana.yml need to be updated to their modern equivalents. See <<settings,Configuring Kibana>> for accepted configurations.
=== Time-interval based index patterns are no longer supported
*Details:* Starting in Kibana 6.0.0 we removed the ability to create index patterns that use a date-pattern and interval to identify Elasticsearch indices. Index patterns must now use wildcards which are more performant in most cases.
*Impact:* Existing index patterns and saved objects will continue to function without issue, and in a subsequent release we will provide utilities to migrate your index patterns/saved objects.
