Help Parsing Long Integer from Input in Win32 API (Possible Error?)

Hi,

The numbers you’re seeing are not real Win32 error codes. They’re long integers being carried around and then displayed in multiple places (error message, method call, “line” number).

It seemed to be a common issue in some recent post:

https://learn.microsoft.com/en-us/answers/questions/5552294/unexpected-api-response-error-16464-need-clarifica

https://learn.microsoft.com/en-us/answers/questions/5543970/unexpected-api-response-error-need-clarification

https://learn.microsoft.com/en-us/answers/questions/5535293/getting-error

All of these posts seem to show that the long error you're getting is regarding some parameter passed into or internal working of ProcessRequest() function

Typical Win32 errors are 32‑bit values and usually small. Values like 18884001969 or 18883190814 are far outside what you would normally see and don’t map to named Win32 constants.

A source file having that many lines is kind of hard to believe (please do let me know if that is the case).

The error might be logged using a helper like this

   throw new InvalidOperationException(

       $"Operation failed with error code {code}");

which are reused across multiple layers (controller, logger, service, etc.).

Based on that and your title, what I guess is happenning is:

• There is a long integer (some ID or value from input) that your code treats as an “error code”.
• That value is being:
  • parsed from input (string -> long),
  • passed into ProcessRequest(...) (hence things like ProcessRequest(18882749655))
  • Then interpolated into the exception message (Operation failed with error code …)

A correct approach would be:

• Parse safely:

  
    if (!long.TryParse(inputString, out var value))
  
    {
  
        // handle invalid numeric input (log, return 400, etc.)
  
    }
  
  

• Validate the range if it’s supposed to be an error code or 32‑bit value:

    
    if (value < 0 || value > int.MaxValue)
    {
    // out of expected range
    }
    
    int code = (int)value;
    
  

• If you really want a Win32 error, don’t get it from arbitrary input at all; use:

  
    int win32Error = Marshal.GetLastWin32Error();
  
  

Hope this helps.