Black Lines Appear After PDF Export

[Cr_burch]

When I export my Indesign document to PDF (print or interactive, various compatabilies) I get these random small black lines appear on random pages. Doesn't seem to be associated with certain symbols. Any ideas?

[Eugene Tyson]

Hard to know what's going on with that.

Any chance of a sample file?

Try resetting your preferences:
The easiest way to reset everything is to delete the InDesign preferences: as soon as InDesign starts to boot hold down Shift, Alt, Ctrl (and Apple/Cmd if working on a Macintosh). A dialog will appear asking to delete the InDesign Preferences, select 'Yes' on this dialog.
Further info and instructions here if needed:
https://helpx.adobe.com/in/indesign/kb/indesign-preferences-support-file-locations.html

or

If a document is not behaving well then try 

File>Export 

Choose IDML

Open the IDML in InDesign
Save the file as a new InDesign file with a new name
See if the issue persists.

[Laubender]

Hi Cr_burch,

wild guess: it's a non-def glyph. A stand-in for a character that InDesign cannot render on the page.

The shape of that sort of thing could be different. It depends on the used font and the font designers.

Some do a little box, some do a little box with an X in it, some do an X only, some leave it out of a font entirely.

I assume you are faced with a bug that has to do with font installation.

Uninstall the font, reinstall it. Or make it only available through InDesign's Fonts folder in the Application folder.

Related could be the following discussion ( and others that show similar issues ) :

Quote marks displaying incorrectly in exported PDF from InDesign
fosforuscw, Dec 05, 2021
https://community.adobe.com/t5/indesign-discussions/quote-marks-displaying-incorrectly-in-exported-p...

Regards,
Uwe Laubender

( ACP )