Briefly, this error occurs when Elasticsearch is unable to parse a date/time field because it’s not in the expected format. Elasticsearch expects date fields to be either a number or a string in a specific format. To resolve this issue, ensure that the date/time field is in the correct format. If it’s a string, it should follow the ISO 8601 format. If it’s a number, it should be the number of milliseconds since the Unix epoch. Also, check your mapping to ensure the field is correctly defined as a date type.
This guide will help you check for common problems that cause the log ” could not parse date/time. expected date field [{}] to be either a number or a ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin.
Log Context
Log “could not parse date/time. expected date field [{}] to be either a number or a” class name is WatcherDateTimeUtils.java. We extracted the following from Elasticsearch source code for those seeking an in-depth context :
}
if (token == XContentParser.Token.VALUE_STRING) {
try {
return parseDateMath(parser.text(); timeZone; clock);
} catch (ElasticsearchParseException epe) {
throw new ElasticsearchParseException("could not parse date/time. expected date field [{}] to be either a number or a " +
"DateMath string but found [{}] instead"; epe; fieldName; parser.text());
}
}
if (token == XContentParser.Token.VALUE_NULL) {
return null;
