On the first and last page of this PDF there is text in a blue block that fails to render.
No errors listed in the error console.
I'm not sure what this "blue block" you are describing is. I don't see it in Adobe Reader either. Mind posting a screenshot?
Finally got pdf.js / Firefox settings to get the error message.
[11:37:29.617] Warning: AcroForm/XFA is not supported
Looks like this depends on issue #2373 or #1459
[16:13:01.318] "PDF a6a91a1ed0681e61dba04a3fddc52030 1.4 Acrobat PDFWriter 5.0 for Windows NT / Print"
[16:13:01.318] "Warning: AcroForm/XFA is not supported"
Still loads the basic bits of the PDF.