How to troubleshoot when JMeter’s JSON extractor cannot retrieve any values?

If the JSON extractor in JMeter fails to extract a value, there could be several reasons and corresponding solutions:

1. Verify if the JSON path is correct: Make sure that the JSON path entered in the “JSON path expression” field of the extractor is correct. You can view the returned JSON data in the browser’s developer tools and use that tool to validate the JSON path.
2. To verify if the response data is in JSON format: when using the JSON Extractor in JMeter, the response data must be valid JSON format. Use JMeter’s Debug Sampler to view the contents of the response data to ensure it is valid JSON format.
3. Validate the scope of the extractor: Make sure the scope of the JSON extractor is correctly configured. If the extractor runs after a sampler, set the scope to “Previous Sampler’s scope.” If the extractor runs before a sampler, set the scope to “Current Thread Group.”
4. Verify the reference name of the extractor: Make sure the “reference name” field of the extractor is filled with a valid variable name. The extracted value will be stored in this variable and can be used in subsequent requests.
5. Use a debugging tool: You can use JMeter’s Debug Sampler to validate the configuration and functionality of the extractor. Add the Debug Sampler to the test plan, run the test, and check the debug information to understand if the extractor is executing correctly.

I hope the above solutions can help you solve the problem. If the issue still persists, please provide more detailed information so that we can assist you better.