### Translation of the Problem
When exporting a file, the following error occurred: `listenerStart Error`, and the request failed with an exception:
```
Servlet failed with Exception java.lang.NullPointerException
at weblogic.servlet.internal.ServletResponseImpl.sendError(ServletResponseImpl.java:610)
at org.apache.struts2.dispatcher.Dispatcher.sendError(Dispatcher.java:770)
at org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:505)
at org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:77)
at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:91)
Truncated. See log file for complete stacktrace.
```
---
#### Supplementary Question 1:
Is this log file the `catalina.out` file in Tomcat? If not, which file is it, and where is it located? The server uses WebLogic, and I am unfamiliar with it. Please provide guidance.
---
#### Supplementary Question 2:
When issuing a "file export" request on the page, an `IdentifierGenerationException` occurs. It calls a method in the action class. In the `catalina.out` log, there is no print information related to this method. I suspect that the request did not even reach the method in the action class and may have failed earlier. Normally, exception logs indicate the specific line of code causing the issue, but this exception does not. Could this be the case? I currently have no idea how to investigate further. What does the error code look like?
---
#### Supplementary Question 3:
I think it's like this: more detailed log information is as follows:
Other logs are indeed printed by `log4j`. Is the error code "BEA-101020" helpful for troubleshooting?
---
#### Supplementary Question 4:
There is only one interceptor in the project, which handles permission verification. Only logged-in users can operate the system. There are no other interceptors. Could the issue be related to a custom interceptor?
---
#### Supplementary Question 5:
Yes, in this project, only this request has issues, while others work fine. Moreover, when testing the same code on a Tomcat server, it works without problems.
---
#### Supplementary Question 6:
Thank you for your help! Would it be convenient to discuss via QQ? You can add me at 270323916.
---
#### Suggestions from Other Users:
1. **Check the Log File**: Look into the log file mentioned in the error message (`see log file for complete stacktrace`) for more details.
2. **Examine the Code**: What does the problematic code look like?
3. **Review Configuration**: Check the configuration of this request.
4. **Special Features**: Is there anything special about this request compared to others?
5. **JSTL/EL Usage**: Are JSTL or EL used on the page?
6. **Debugging Tools**: Consider debugging tools or references, such as the link provided regarding `debug assertion failed`.
---
#### Additional Notes:
The issue seems to stem from either:
- A misconfiguration in the WebLogic environment,
- A problem with the interceptor or permission handling,
- Or a mismatch between the application and the WebLogic server setup.
Further investigation into the logs and configurations will likely reveal the root cause.