1. Embed all fonts. Embedding ensures that fonts aren’t substituted.
2. Open the PDF document in Adobe Acrobat.
3. ​Choose Tools then scroll down to the Print Production Icon and on the ADD dropdown choose open and locate the file.
4. Then choose Preflight in the right panel.
5. One the Preflight window is open in you will pick Prepress, Color, and Transparency from the top dropdown.
6. Then on the lower right you will click analyze.
7. This will prompt you with errors that need to be corrected.