Question

I'm working on a Windows Service and I'm trying to write a Byte[] to a already existing File with a normal FileStream. My Code looks like this:

byte[] attachBytes = attach.Data;

FileInfo info = new FileInfo(@"C:\Users\User\Documents\" + attach.Filename);

FileStream stream = info.Create();

stream.Write(attachBytes, 0, attachBytes.Length);

The exception message is:

Buffer cannot be null. Parameter name: array

Has anyone an idea what's going on here?

Additional info: byte[] comes from a .msg file which I'm reading with this library. I'm looping through the attachments of the .msg file and saving them in a directory. .NET 4.5.2, Desktop Enviroment. I've tested the code in a console application and it works perfectly. But in my WindowsService project the error occurs.
EDIT:
Stacktrace:

    Source: mscorlib Message: A call target caused an exception error. StackTrace:  
   at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)  
   at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)  
   at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)  
   at Source: mscorlib Message: Buffer cannot be null.
Parametername: array StackTrace:
   at System.IO.FileStream.Write(Byte[] array, Int32 offset, Int32 count)

Answer 1

以下是“公共重写无效Write（byte []数组，int偏移量，int计数）”方法的源代码：https://referencesource.microsoft.com/#mscorlib/system/io/filestream.cs行1751。在链接中为源代码授予了.NET版本。是4.7.2，我认为您的错误情况代码不会有所不同。

只有当传递给Write方法的'array'参数为null时，才从FileStream.Write（...）引发ArgumentNullException。

考虑“ attach.Data”可能确实返回null的可能性。关于“ attach.Data”，我们应该了解什么特别的东西？

c# Buffer cannot be null. Parameter name: array

1 个答案: