.net - Elastic Search attempts to parse a non-date filed as date based on its value

Question

Using NEST with .NET Core we're getting the following error:

failed to parse field [UniqueId] of type [date] in document with id '123456'. Preview of field's value: '4524395.3.6-0'" CausedBy: "Type: illegal_argument_exception Reason: "failed to parse date field [4524395.3.6-0] with format [strict_date_optional_time||epoch_millis]" CausedBy: "Type: date_time_parse_exception Reason: "Failed to parse with all enclosed parsers"""

UniqueId is a string field, here's the part of the index for it:

 "UniqueId" : {
                  "type" : "text",
                  "fields" : {
                    "keyword" : {
                      "type" : "keyword",
                      "ignore_above" : 256
                    }
                  }
                },

How do we stop elastic from attempting to parse it?

Answer 1

Your mapping contains several externalUniqueId fields (at different hierarchy levels), and all of them are of type text/keyword, except one which is of type date (in parents.labour).

That's the one causing the issue you're seeing. You need to fix the mapping of that field, and reindex the whole index in order to make this work.