Addressing Cs0011: Understanding And Fixing External Exception Errors

Addressing CS0011: Understanding and Fixing External Exception Errors


External exception errors occur when the compiler encounters a situation where it cannot guarantee the safety of the generated code. These errors are often caused by calling unmanaged code that may throw exceptions that the CLR cannot handle.

Identifying CS0011 Errors

External exception errors are typically identified by the error code CS0011, which is displayed in the compiler output. The error message typically includes a description of the situation that caused the error, such as “Calling unmanaged code that can throw .”

Causes of CS0011 Errors

The most common cause of CS0011 errors is calling unmanaged code that may throw exceptions that the CLR cannot handle. This can occur when working with Win32 APIs, COM components, or other types of native code. Additionally, CS0011 errors can also be caused by using unsafe code or pointer arithmetic.

Fixing CS0011 Errors

The key to fixing CS0011 errors is to ensure that the unmanaged code being called is properly managed. This can be done by using platform invoke (P/Invoke) to explicitly declare the unmanaged function and specify the calling convention and marshalling behavior. Additionally, it is important to handle any potential exceptions that may be thrown by the unmanaged code using a try/catch block.


External exception errors can be challenging to troubleshoot, but they can be resolved by carefully examining the error message and taking steps to ensure that unmanaged code is properly managed. By using P/Invoke and implementing proper exception handling, developers can avoid CS0011 errors and ensure the safety of their code.# Addressing Cs0011: Understanding and Fixing External Exception Errors

Executive Summary

CS0011 is a compiler error that can occur in C# when an external exception is not handled. Understanding and fixing this error requires a solid grasp of external exceptions, exception handling, and the stack trace generated by the error.


External exceptions are exceptions that are thrown outside of the current program’s control. External exceptions are re-thrown by the runtime system with the addition of an “Inner Exception” object that points to the original exception. Unhandled exceptions thrown from deeply nested internal function calls, or from asynchronous callbacks, have the same semantics as if they had been thrown from a lower level, or from an external source. They too become external exceptions.

Understanding External Exception Errors

1. Identifying External Exception Errors

  • Error Message: Look for the CS0011 error message in your code, indicating an unhandled external exception.

  • Stack Trace: Examine the stack trace provided with the error message to identify the source of the exception.

2. Unhandled Exceptions in Program Flow

  • Inner Exception: External exceptions usually contain an “Inner Exception” object that points to the original exception.

  • Exception Handling Blocks: Ensure you have appropriate exception handling blocks (try-catch) in place to catch external exceptions.

3. Asynchronous Callbacks and External Exceptions

  • Background Tasks: External exceptions may arise from asynchronous callbacks or background tasks that run outside the normal program flow.

  • Event Handlers: Event handlers may throw exceptions asynchronously, leading to external exceptions if unhandled.

4. Unloading AppDomains and External Exceptions

  • AppDomain Unloads: External exceptions may occur when unloading AppDomains (isolated execution environments) if there are unhandled exceptions in threads running in the AppDomain.

  • Thread Termination: Exceptions thrown during thread termination can also cause external exceptions.

5. JIT Compilation and External Exceptions

  • Just-In-Time Compilation (JIT): During JIT compilation, exceptions can occur while loading or executing methods, leading to external exceptions.

  • Native Code Execution: Exceptions thrown during native code execution can also cause external exceptions.


External exceptions can be tricky to debug and resolve. By understanding the causes of CS0011 errors, developers can efficiently handle exceptions, avoiding unexpected program termination and ensuring a stable and reliable application.

Keyword Phrase Tags

  • CS0011
  • External Exception
  • Exception Handling
  • Asynchronous Callbacks
  • Stack Trace
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Comments 9
  1. I have no idea what are you talking about but I will give it a try anyway

  2. Hey guys, I am am not sure if you know that this article was translated using automated software, its original language is Czech.

  3. Let me get this str8. You are telling me that is a programing error??? This is definitely something a computer programer like me must now!

  4. This software sucks, is always giving me problems like this. I really wish I could throw it out the window.

  5. I cannot belive people over look these kinds of problems, it is super important and it needs to be fixed right away!

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