KB-2256 Kafka fails to start on Windows after applying hotfix

Symptoms

After applying a hotfix released between June 5, 2023 and Oct 20, 2023 on Appian 21.3 and later, Kafka fails to start on Windows and prevents site startup.

• Zookeeper is able to start
• The following message is repeated in the console output during Kafka startup 

waiting for process Kafka
waiting for process Kafka
waiting for process Kafka
waiting for process Kafka

• Eventually, the following errors are displayed in the console output

Service Kafka failed to start
Error running script: Unable to start transaction log.
Unable to start distributed transaction log. Check the Kafka and Zookeeper logs for more information.
com.appian.komodo.StartKomodo$TransactionLogNotStartedException: Unable to start transaction log.

Cause

Self-managed hotfix packages meant for Windows contained the Unix Kafka version instead of the Windows version. This incompatibility caused Kafka to fail startup for sites using these hotfixes.

Action

For hotfixes released on Nov 3, 2023 and later, hotfix packages for Windows and Linux are separated. Starting from the following hotfixes from 21.4 to 23.3, pick the relevant hotfix package for your Operating System (Linux/Windows) accordingly and follow the updated instructions to apply the hotfix.

• 21.4.2327.0
• 22.1.2047.0
• 22.2.1727.0
• 22.3.1502.0
• 22.4.1307.0
• 23.1.967.0
• 23.2.712.0
• 23.3.441.0

To apply one of the following hotfixes released between June 5, 2023 and Oct 20, 2023, follow the manual steps below for respective OS to function successfully.

• 21.3.2160.0 to 21.3.2310.0
• 21.4.1915.0 to 21.4.2300.0
• 22.1.1630.0 to 22.1.2026.0
• 22.2.1315.0 to 22.2.1706.0
• 22.3.1075.0 to 22.3.1466.0
• 22.4.850.0 to 22.4.1266.0
• 23.1.525.0 to 23.1.926.0
• 23.2.235.0 to 23.2.671.0
• 23.3.205.0 to 23.3.396.0

Windows Hotfixes (June 5, 2023 - Oct 20, 2023)

1. If the hotfix has been attempted but failed, please ensure that you have a full system backup taken prior to the hotfix, and then proceed to restore the backup.

2. Download the latest hotfix package for your Appian installation.

3. The kafka-server_<version>-appian-<number>.tgz at the root of the hotfix package contains the correct version. 

   1. Follow the steps from the hotfix installation up until (and including) the step to unzip updates.zip.
   2. Under <APPIAN_HOME>/services, delete all kafka-<version> directories.
   3. Unzip kafka-server_<version>-appian-<number>.tgz and move the generated kafka-<version> directory (the path would look like <APPIAN_HOME>/Hotfix Version <version>/kafka-server-<version>/kafka-server-<version>/kafka-<version>) into <APPIAN_HOME>/services. 
   4. Delete kafka-server_<versdion>-appian-<number>.tgz
   5. Proceed with the remaining steps to install the hotfix as normal.

Linux Hotfixes (June 5, 2023 - Oct 20, 2023)

No action is required as the kafka-server_<version>-appian-<number>.tgz at the root of the hotfix package is not utilized during hotfix application on Linux. If your Appian runs in a Linux environment, please feel free to ignore the kafka-server_<version>-appian-<number>.tgz or delete it at the end of hotfix application.

Affected Versions

This article applies to self-managed Appian 21.3 and later hosted on Windows.

Last Reviewed: November 2023