165: Expandable-section heading not closed

You started the block with either +++ or + +, followed by content. This creates an expandable-section heading or expandable-subsection heading respectively, which is a heading whose associated section can be toggled visible or hidden. However, you did not end the heading with the same three characters, which is expected.

Solution

Make sure to end the heading with the same three characters that you used at its start. If you did not mean to create a heading, but want to use these characters at the start of a paragraph literally, you can prepend them with a backslash, for example: \+++

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