Hi @hamzashaikh,
An “Invalid PDF Structure” error could happen for a multiple of reasons:
- theme reformatting the shortcode quotes ” into curly quotes (take a look in the Text tab of the editor if you aren’t using the PDF block with the new WP 5+ editor, do you see straight quotes or curly ones,
- SSL inconsistencies between the back and front ends of the site (both the front and back end should share the same HTTP or HTTPS protocol),
- excessively large PDFs causing the server to time out (compressing the size of your PDF using a service such as https://www.ilovepdf.com/compress_pdf is very effective),
- corruption of the PDF document itself, or
- the file URL not being entered into a manual shortcode.
Are you experiencing this issue with all of your PDFs or only with certain ones? If it is only certain ones then the size or corruption of the document is the most likely cause.
Emma