Letters are being replaced with squares

[TandyCPH]

Adobe Acrobat XI Pro - When inserting pages into a document, some of the font is turning into small squares. How can I stop this from happening?

[Karl Heinz Kremer · Accepted solution]

If this happens after you merge PDF files (or insert one into another), this is usually a sign of a font problem. See here for a potential workaround: Workaround for Missing Characters After Merging PDF Files