PAC 2 Error
Font not embedded
PDF/UA > Basic Requirements > Fonts > Font Embedding
Matterhorn Protocol Checkpoint 31-009: For a font used by text intended to be rendered the font program is not embedded.
In Acrobat Pro, Tools > Print Production > Preflight > expand “PDF Fixups” > select “Embed Fonts” > click “Analyze and fix”. This suggestion will not work if the font is licensed such that embedding is forbidden. In that case hopefully you have access to the source document and can use a different font.
Video version of this suggestion: