# @timestamp - Epoch - Illegal Date Format exception
**URL:** https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261
**Category:** Logstash
**Created:** [May 2, 2018, 2:19pm UTC](https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261 "2018-05-02T14:19:05Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@SKumarMN](https://discuss.elastic.co/u/SKumarMN)
#### Post date: [May 2, 2018, 2:19pm UTC](https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261/1 "2018-05-02T14:19:05Z")
Hi All,
ES index is having a field with the mapping as below.
"@timestamp": {
"format": "epoch\_millis",
"type": "date"
}
From logstash i want to populate this field with custom timestamp obtained from input document. The custom time stamp is in millis and i have used the filter
date{
match =\> ["time\_mills","UNIX\_MS"]
target =\>"@timestamp"
}
however during indexing it fails complaining the time format issue. Can you please help
---
### Author:  [@magnusbaeck](https://discuss.elastic.co/u/magnusbaeck)
#### Post date: [May 2, 2018, 4:37pm UTC](https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261/2 "2018-05-02T16:37:05Z")
The date filter always produces an ISO8601 timestamp that can't be stored in your `@timestamp` field.
If you already have the time in milliseconds in the `time_millis` field, why would you need a date filter? Just copy the field value to the `@timestamp` field.
---
### Author:  [@SKumarMN](https://discuss.elastic.co/u/SKumarMN)
#### Post date: [May 3, 2018, 12:00pm UTC](https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261/3 "2018-05-03T12:00:33Z")
I had tried the below but got the same issues hence went with date filter
filter {
mutate {
copy =\> { "time\_millis" =\> "@timestamp" }
}
}
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [May 31, 2018, 12:00pm UTC](https://discuss.elastic.co/t/timestamp-epoch-illegal-date-format-exception/130261/4 "2018-05-31T12:00:36Z")
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