Looking at your code, you probably haven't indented below line properly: System.TypeInitializationException occurred You need to indent your code by four spaces, or select it all and press the `{}` button. Also make sure there is one blank line between your last line of text and your first line of code. This will cause your code to be rendered in `<pre><code>` blocks and all of its HTML/Markdown entities will be escape/ignored respectively. Properly indented code renders like this: #include <iostrea> int main() { vector<int> items; } Unindented code renders like this: > # include <isotream> > > int main() { vector<int> items; } You can see why we stress proper indenting of code.