---
title: Application Reset Tool
description: 
weight: 13
tags: ['kafka', 'docs']
aliases: 
keywords: 
type: docs
---

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You can reset an application and force it to reprocess its data from scratch by using the application reset tool. This can be useful for development and testing, or when fixing bugs.

The application reset tool handles the Kafka Streams [user topics](manage-topics.html#streams-developer-guide-topics-user) (input, output, and intermediate topics) and [internal topics](manage-topics.html#streams-developer-guide-topics-internal) differently when resetting the application.

Here's what the application reset tool does for each topic type:

  * Input topics: Reset offsets to specified position (by default to the beginning of the topic).
  * Intermediate topics: Skip to the end of the topic, i.e., set the application's committed consumer offsets for all partitions to each partition's `logSize` (for consumer group `application.id`).
  * Internal topics: Delete the internal topic (this automatically deletes any committed offsets).



The application reset tool does not:

  * Reset output topics of an application. If any output (or intermediate) topics are consumed by downstream applications, it is your responsibility to adjust those downstream applications as appropriate when you reset the upstream application.
  * Reset the local environment of your application instances. It is your responsibility to delete the local state on any machine on which an application instance was run. See the instructions in section Step 2: Reset the local environments of your application instances on how to do this.



Prerequisites
    

  * All instances of your application must be stopped. Otherwise, the application may enter an invalid state, crash, or produce incorrect results. You can verify whether the consumer group with ID `application.id` is still active by using `bin/kafka-consumer-groups`. When long session timeout has been configured, active members could take longer to get expired on the broker thus blocking the reset job to complete. Use the `--force` option could remove those left-over members immediately. Make sure to shut down all stream applications when this option is specified to avoid unexpected rebalances.

  * Use this tool with care and double-check its parameters: If you provide wrong parameter values (e.g., typos in `application.id`) or specify parameters inconsistently (e.g., specify the wrong input topics for the application), this tool might invalidate the application's state or even impact other applications, consumer groups, or your Kafka topics.

  * You should manually delete and re-create any intermediate topics before running the application reset tool. This will free up disk space in Kafka brokers.

  * You should delete and recreate intermediate topics before running the application reset tool, unless the following applies:

>     * You have external downstream consumers for the application's intermediate topics.
>     * You are in a development environment where manually deleting and re-creating intermediate topics is unnecessary.




# Step 1: Run the application reset tool

Invoke the application reset tool from the command line

Warning! This tool makes irreversible changes to your application. It is strongly recommended that you run this once with `--dry-run` to preview your changes before making them.
    
    
    $ bin/kafka-streams-application-reset

The tool accepts the following parameters:
    
    
    Option (* = required)                 Description
    ---------------------                 -----------
    * --application-id <String: id>       The Kafka Streams application ID
                                            (application.id).
    --bootstrap-server <String: server to  REQUIRED unless --bootstrap-servers
                                connect to>                            (deprecated) is specified. The server
                                             (s) to connect to. The broker list
                                             string in the form HOST1:PORT1,HOST2:
                                             PORT2.
    --bootstrap-servers <String: urls>     DEPRECATED: Comma-separated list of
                                             broker urls with format: HOST1:PORT1,
                                             HOST2:PORT2 (default: localhost:9092)
    --by-duration <String: urls>          Reset offsets to offset by duration from
                                            current timestamp. Format: 'PnDTnHnMnS'
    --config-file <String: file name>     Property file containing configs to be
                                            passed to admin clients and embedded
                                            consumer.
    --dry-run                             Display the actions that would be
                                            performed without executing the reset
                                            commands.
    --from-file <String: urls>            Reset offsets to values defined in CSV
                                            file.
    --input-topics <String: list>         Comma-separated list of user input
                                            topics. For these topics, the tool will
                                            reset the offset to the earliest
                                            available offset.
    --intermediate-topics <String: list>  Comma-separated list of intermediate user
                                            topics (topics used in the through()
                                            method). For these topics, the tool
                                            will skip to the end.
    --internal-topics <String: list>      Comma-separated list of internal topics
                                            to delete. Must be a subset of the
                                            internal topics marked for deletion by
                                            the default behaviour (do a dry-run without
                                            this option to view these topics).
    --shift-by <Long: number-of-offsets>  Reset offsets shifting current offset by
                                            'n', where 'n' can be positive or
                                            negative
    --to-datetime <String>                Reset offsets to offset from datetime.
                                            Format: 'YYYY-MM-DDTHH:mm:SS.sss'
    --to-earliest                         Reset offsets to earliest offset.
    --to-latest                           Reset offsets to latest offset.
    --to-offset <Long>                    Reset offsets to a specific offset.
    --force                               Force removing members of the consumer group
                                          (intended to remove left-over members if
                                          long session timeout was configured).

Consider the following as reset-offset scenarios for `input-topics`:

  * by-duration
  * from-file
  * shift-by
  * to-datetime
  * to-earliest
  * to-latest
  * to-offset



Only one of these scenarios can be defined. If not, `to-earliest` will be executed by default

All the other parameters can be combined as needed. For example, if you want to restart an application from an empty internal state, but not reprocess previous data, simply omit the parameters `--input-topics` and `--intermediate-topics`.

# Step 2: Reset the local environments of your application instances

For a complete application reset, you must delete the application's local state directory on any machines where the application instance was run. You must do this before restarting an application instance on the same machine. You can use either of these methods:

  * The API method `KafkaStreams#cleanUp()` in your application code.
  * Manually delete the corresponding local state directory (default location: `/tmp/kafka-streams/<application.id>`). For more information, see [Streams](/39/javadoc/org/apache/kafka/streams/StreamsConfig.html#STATE_DIR_CONFIG) javadocs.



  * [Documentation](/documentation)
  * [Kafka Streams](/documentation/streams)
  * [Developer Guide](/documentation/streams/developer-guide/)


