# Force! Logstash keeps restarting

**URL:** <https://discuss.elastic.co/t/force-logstash-keeps-restarting/278624>\
**Category:** Logstash\
**Tags:** elastic-stack-monitoring\
**Created:** [July 14, 2021, 7:37am UTC](https://discuss.elastic.co/t/force-logstash-keeps-restarting/278624 "2021-07-14T07:37:24Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![rojin](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/rojin/32/97697_2.png) [@rojin](https://discuss.elastic.co/u/rojin)\
**Post date:** [July 14, 2021, 7:37am UTC](https://discuss.elastic.co/t/force-logstash-keeps-restarting/278624/1 "2021-07-14T07:37:24Z")

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Hi! Two of the logstash instances keep restarting giving this error in the log. The other is OK and does not. Can someone help me?

```auto
[2021-07-14T11:58:40,333][FATAL][logstash.runner] An unexpected error occurred! {:error=>java.lang.IllegalStateException: java.util.ConcurrentModificationException, :backtrace=>["org.logstash.execution.WorkerLoop.run(org/logstash/execution/WorkerLoop.java:85)", "jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)", "jdk.internal.reflect.NativeMethodAccessorImpl.invoke(jdk/internal/reflect/NativeMethodAccessorImpl.java:62)", "jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(jdk/internal/reflect/DelegatingMethodAccessorImpl.java:43)", "java.lang.reflect.Method.invoke(java/lang/reflect/Method.java:566)", "org.jruby.javasupport.JavaMethod.invokeDirectWithExceptionHandling(org/jruby/javasupport/JavaMethod.java:425)", 
"org.jruby.javasupport.JavaMethod.invokeDirect(org/jruby/javasupport/JavaMethod.java:292)", "usr.share.logstash.logstash_minus_core.lib.logstash.java_pipeline.start_workers(/usr/share/logstash/logstash-core/lib/logstash/java_pipeline.rb:243)", "org.jruby.RubyProc.call(org/jruby/RubyProc.java:295)", "org.jruby.RubyProc.call(org/jruby/RubyProc.java:274)", "org.jruby.RubyProc.call(org/jruby/RubyProc.java:270)", "java.lang.Thread.run(java/lang/Thread.java:834)"]}

```

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\
**Post date:** [August 11, 2021, 7:37am UTC](https://discuss.elastic.co/t/force-logstash-keeps-restarting/278624/2 "2021-08-11T07:37:47Z")

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