PDFresh guide
Why Can't I Copy Text from a PDF?
Understand why PDF text cannot be copied, including image-only scans, missing text layers, font encoding problems, and copy restrictions.
Image-only scans
A scanned page may be only a picture of text. If there is no text layer, a text extractor will find little or nothing.
Missing or damaged text layer
Some PDFs contain visual text but no usable embedded text. Others have broken font encoding that copies as incorrect characters.
Mixed PDFs
A long PDF can contain selectable text on some pages and image-only scans on others.
Use PDFresh
Open Extract PDF Text to check whether the PDF has extractable text. If it returns no useful text, you probably need OCR.
Limitations
PDFresh does not bypass restrictions, perform OCR, translate text, or fix font encoding.