For each PDF/A-1 validation issue we try to explain what it means and, if possible how to resolve it. For a more technical explanation of the issue we quote the related section of the ISO 19005-1 PDF/A Specification.
The encoding of font characters to glyphs used in the document is missing or does not match the encoding in the font dictionary of the document.
How can I fix it?
Use a PDF creation product that correctly encodes and embeds all fonts. We recommend Solid PDF Creator Plus.
6.3.3.3 - ISO 19005-1 PDF/A Specification:
All CMaps used within a conforming file, except Identity-H and Identity-V, shall be embedded in that file as described in PDF Reference 5.6.4. For those CMaps that are embedded, the integer value of the WMode entry in the CMap dictionary shall be identical to the WMode value in the embedded CMap stream.