Argument Null Exception when saving an EML after removing an attachement.

[sven-peeters-stitchd-be]

When removing an attcahement from a loaded EML, it throws an argument null exception during the Save operation.

var msg = MsgReader.Mime.Message.Load(new FileInfo("C:\\Users\\A1055101\\Downloads\\test.eml"));
msg.Attachments.RemoveAt(1);
msg.Save(new FileInfo("C:\\Users\\A1055101\\Downloads\\test_clean2.eml"));

"Value cannot be null. (Parameter 'value')" at System.Net.Mime.MimeBasePart.set_ContentType(ContentType value) at MsgReader.Mime.Message.ToMailMessage() at MsgReader.Mime.Message.Save(Stream messageStream) at MsgReader.Mime.Message.Save(FileInfo file) at Program.

$(String[] args) in C:\Users\A1055101\source\repos\DocaMonTest\DocaMonTest\Program.cs:line 57

[Sicos1977]

Weird I had a check for it in the code and then resharper complained it was not needed so I removed it. And now the code gives that error :-) .... Always nice a tool that has a split personality

[Sicos1977]

See version 5.4.3 .... also test now :-)

[Sicos1977]

There is no save method in the MailMessage class so I had to use a reflection example from the internet but as usual this works different if you are on the .net framework or .net 5 and 6 so I had to build that in to.... so it took me a while :-)

[sven-peeters-stitchd-be]

Throwing a different error now :-( Using .Net6

NullReferenceException: Object reference not set to an instance of an object. This exception was originally thrown at this call stack: System.Net.Mail.Message.PrepareEnvelopeHeaders(bool, bool) System.Net.Mail.Message.Send(System.Net.Mime.BaseWriter, bool, bool) System.Net.Mail.MailMessage.Send(System.Net.Mime.BaseWriter, bool, bool)

[Sicos1977]

It is probably because the reflection works somewhat different in .net 6. I'll have to make a .net 6 test app because the app I used is .net core 3 so there is probably a difference between those .net versions. I'll try to look into this tomorrow today I have to finished something else.

[Sicos1977]

It seems not to be the reflection, I just updated the test project to also target .net 6 and this one worked without any problems with the em file I used

[Sicos1977]

I think it is best that you clone my repository to your local development machine and debug the code yourself to see what is going wrong with your eml file.

[Sicos1977]

No response.... closed