Resolving java.lang.IllegalStateException in Nifi Registry 0.8 on Windows Server

Описание: Discover how to fix the `java.lang.IllegalStateException` error when running Nifi Registry 0.8 on Windows Server with Java 15, ensuring smooth installation and setup.
---
This video is based on the question https://stackoverflow.com/q/68399289/ asked by the user 'tmlai' ( https://stackoverflow.com/u/3402724/ ) and on the answer https://stackoverflow.com/a/68473489/ provided by the user 'tmlai' ( https://stackoverflow.com/u/3402724/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Nifi Registry 0.8 throws java.lang.IllegalStateException: Unable to load cache item

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting Nifi Registry 0.8 on Windows Server: A Deep Dive into java.lang.IllegalStateException

If you're trying to run Nifi Registry 0.8 on a Windows Server using Amazon Corretto 15, it's not uncommon to stumble upon some challenging errors. One such notable issue is the java.lang.IllegalStateException: Unable to load cache item. This happens especially in environments where Nifi Registry isn't officially supported, yet many users have reported success. So, how can you tackle this problem effectively? Let's break down the solution.

Understanding the Error

When you attempt to start Nifi Registry using the run-nifi-registry.bat file, you may encounter the following error:

[[See Video to Reveal this Text or Code Snippet]]

This error indicates that there is a failure in loading the Java Architecture for XML Binding (JAXB) implementation, which is crucial for XML processing in Java applications. The stack trace shows that the error happens because the required JAXB classes cannot be found.

Causes of the Issue

JAXB Not Present: Nifi Registry may rely on JAXB but the implementation for it is missing from your Java 15 setup.

Java Version Compatibility: Since Nifi Registry was developed with earlier versions of Java in mind, certain dependencies may not be compatible with newer versions, like Java 15.

Classpath Issues: The required jars might not be correctly set in the classpath for the Java application.

The Solution Breakdown

To address this issue effectively, here’s a step-by-step guide to getting Nifi Registry up and running without errors.

Step 1: Verify the JAXB Implementation

Nifi Registry should ideally come bundled with the necessary JAXB implementation jars. Check for the presence of a directory named:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Copy Required JAR Files

Most likely, the JAXB implementation files are located there, but since you're using Java 15, they might not be loading correctly. To ensure that your application can access these files:

Locate the required JAR files:

Navigate to the directory mentioned above.

Look for jars related to JAXB (for example, jakarta.xml.bind-api and jaxb-runtime).

Copy the JAR files:

Move these files from <install-dir>\lib\java11 to <install-dir>\lib.

Step 3: Update Log Level (If Needed)

For better insight during troubleshooting, you can set the log level to TRACE. This will help you confirm whether the necessary jars are loading or if there are other underlying issues.

Step 4: Restart Nifi Registry

After making the necessary adjustments:

Try restarting the Nifi Registry again with the run-nifi-registry.bat script.

Monitor the logs for any further errors or confirmations that the JAXB contexts have loaded correctly.

Conclusion

By following these steps, the java.lang.IllegalStateException: Unable to load cache item issue should be resolved, allowing you to run Nifi Registry 0.8 on Windows Server 2019 smoothly. Remember, not all features will be optimized for environments outside of standard support, so always check for community feedback and updates as you navigate through these challenges. Happy coding!