There are several ways to troubleshoot and fix a null pointer exception in Spring Boot:

1. Check for uninitialized variables or objects: Make sure that all variables and objects are initialized before you use them.
2. Check for null values: Make sure that you are not trying to access an object or property of an object that is null.
3. Check for missing dependencies: Make sure that all dependencies are properly added and configured in your project.
4. Debug the code: Use the debugging tools in your IDE to step through the code and identify the line that is causing the null pointer exception.
5. Use try-catch blocks: Wrap the code that may throw the null pointer exception in a try-catch block and handle the exception accordingly.
6. Check the logs: Look at the logs generated by Spring Boot to see if there are any hints about the cause of the null pointer exception.
7. Consult documentation or seek help: If you are unable to fix the null pointer exception on your own, consult the documentation for the library or framework you are using or seek help from other developers or online communities.