# How to troubleshoot "undefined method \`+' for nil:NilClass"
**URL:** https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121
**Category:** Logstash
**Tags:** docker
**Created:** [December 28, 2022, 7:50pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121 "2022-12-28T19:50:25Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@INS](https://discuss.elastic.co/u/INS)
#### Post date: [December 28, 2022, 7:50pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121/1 "2022-12-28T19:50:25Z")
Hi
Maybe You have some idea how to troubleshoot in the long pipeline the bug referring to
`[2022-12-28T19:47:41,016][ERROR][logstash.filters.ruby][main][1b91d552e5ff1ebff261eab8e51449b8aba605255321bb2b70376384a2493180] Ruby exception occurred: undefined method `+' for nil:NilClass {:class=\>"NoMethodError", :backtrace=\>["(ruby filter code):4:in `block in filter_method'", "/usr/share/logstash/vendor/bundle/jruby/2.6.0/gems/logstash-filter-ruby-3.1.8/lib/logstash/filters/ruby.rb:96:in `inline\_script'", "/usr/share/logstash/vendor/bundle/jruby/2.6.0/gems/logstash-filter-ruby-3.1.8/lib/logstash/filters/ruby.rb:89:in `filter'", "/usr/share/logstash/logstash-core/lib/logstash/filters/base.rb:159:in `do\_filter'", "/usr/share/logstash/logstash-core/lib/logstash/filters/base.rb:178:in `block in multi_filter'", "org/jruby/RubyArray.java:1865:in `each'", "/usr/share/logstash/logstash-core/lib/logstash/filters/base.rb:175:in `multi_filter'", "org/logstash/config/ir/compiler/AbstractFilterDelegatorExt.java:134:in `multi\_filter'", "/usr/share/logstash/logstash-core/lib/logstash/java\_pipeline.rb:300:in `block in start_workers'"]}`
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [December 28, 2022, 8:13pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121/2 "2022-12-28T20:13:39Z")
> [@INS](#):
>
> `undefined method `+' for nil:NilClass {:class=\>"NoMethodError", :backtrace=\>["(ruby filter code):4:in `block in filter_method'"`
You have a ruby filter with a code block.
```
ruby {
code => ' a = b + 1 '
}
```
will report that exception with `:backtrace=>["(ruby filter code):2:in`, so you should be looking at the third line of your ruby code.
---
### Author:  [@INS](https://discuss.elastic.co/u/INS)
#### Post date: [December 28, 2022, 8:33pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121/3 "2022-12-28T20:33:11Z")
```auto
ruby {
code => "
event_millisecond = ('000' + event.get('millisecond').to_s).split(//).last(3).join
event.set('event_timestamp', event.get('date') + ' ' + event.get('time') + '.' + event_millisecond)
"
}
```
---
### Author:  [@Badger](https://discuss.elastic.co/u/Badger)
#### Post date: [December 28, 2022, 8:54pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121/4 "2022-12-28T20:54:47Z")
> [@INS](#):
>
> `event.set('event_timestamp', event.get('date') + ' ' + event.get('time') + '.' + event_millisecond)`
OK, so that is the third line of your code. It is processing an event that does not have [date] and/or [time] fields.
---
### Author:  [@system](https://discuss.elastic.co/u/system)
#### Post date: [January 25, 2023, 8:55pm UTC](https://discuss.elastic.co/t/how-to-troubleshoot-undefined-method-for-nil-nilclass/322121/5 "2023-01-25T20:55:45Z")
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