176: Heading text missing

The characters ===, --- or - - at the start and end of a block mark the block as heading. In your case the heading lacks printable content.

Solution

Make sure your heading includes printable content, if you want to use a heading.

The characters --- or - - can also be used to mark a section or subsection break respectively. In this case, make sure --- or - - are the only three characters in the block.

=== I'm a main heading ===

--- I'm a section heading ---

Below is a subsection break:

- -

If you did not mean to create a heading or section break, but want to use these characters literally at the start of a paragraph, you can prepend a backslash: \---