256: Seamless section break without corresponding heading

A block of text in your document contains just the three characters +++ or + +. These mark a seamless section break or seamless subsection break respectively, which end a section or subsection. But in your case a corresponding heading that would have started a (sub)section could not be found.

Solution

In contrast to seamless section breaks, regular section breaks are visible by themselves and can be used without a heading. A regular section break is marked by three hyphens --- instead of plus signs and a regular subsection break by two space-separated hyphens: - -.

If you did not mean to have a section break at all and just want to print literal plus signs, you can prepend a backslash, for example: \+++

If you did mean to mark the end of a section using a seamless section break, make sure that the section has a heading as in the following example:

+++ Details +++

This expandable section is usually not visible but can be
toggled open, if the reader clicks on the expandable-section
heading, in this case "Details".

+++

This is always visible as the expandable section ends above.

Note that sections inside quotation blocks or embedded Aneamal files automatically end at the end of the quotation or embedded file. You do not need to mark the end of an expandable section manually in such a case.