Get the workaround at Safari 7 and 6.1 block PDFs. See Mac OS X Mavericks (10.9) compatibility or Crash during a text search for additional details. For the latest information, see 'Incompatible Software' error | Mac OS X Mavericks (10.9).
In some instances, the Adobe Creative Cloud desktop application encounters an “incompatible software error” and requires a workaround.