Google Docs table of contents not updating? Check the missing heading

Add or rename the heading in the document itself. Click the table of contents so its controls appear, then click the circular Refresh arrow. Click the updated entry to check that it jumps to the right place. Refresh after moving sections as well, especially if the table of contents displays page numbers.

A line can look like a heading because it is large or bold while its paragraph style is still Normal text. Put the cursor on the line and use Format > Paragraph styles to apply the heading level that fits. For example, use Heading 1 for a main section and Heading 2 for a subsection. Refresh the table of contents again.

In a document that uses Pages, click the table of contents and open More options from its controls. Check which heading levels are selected in the panel. A subsection styled as Heading 2 can stay out of the list when the table only shows Heading 1. Google limits table-of-contents formatting in Pageless mode. If you need a page-number layout, switch the document to Pages first.