Unhandled Exception: Access violation writing location 0x00000000

This is a common problem and a moments thought will tell you what the problem is.
Look at the address that it's complaining about: "0x00000000" - or "zero" as it's also known. How likely is it that anything you need to use is going to be located at the first possible address in memory? Absolutely not probable!

So use the debugger and find out why it's zero - which means finding out exactly which bit is zero.
My guess is that your new_node array is not initialized, so it contains zeros - but only you can confirm that as we can't run your code!
When you know that, you can find out why it's zero - probably because you haven't executed the code to actually insert any Msg_t elements into it...

Perhaps try to isolate the error down to the smallest chunk that would create the error; For example, if the Test.cpp code is:

Msg_t *new_node[10];
 
const char *src = "E0";
_strdup(src); //getting access violation error here?

Do you still get the error message here?

Or if that works, how about here? Does that compile fine?

Msg_t *new_node[10];
 
const char *src = "E0";

unsigned char *testresult;

testresult = (unsigned char *) _strdup(src); //getting access violation error here??

Also, you can find some documentation here _strdup, _wcsdup, _mbsdup for _strdup.

It seems like it might already being returning (char *) and perhaps you could just adjust the structure to align with what it is returning.

Explicitly, if the structure is changed to:

typedef struct Msg
{
char   *message_id;
char   *message_name;
}Msg_t;

then does the same issue occur?