PDF file name changes when downloading

Hello!

I hope you are doing well.

Adding to the suggestions already shared above by our Community product experts and Adobe employees. This seems to be an issue specific to Chrome, and it's related to how the browser interprets file names when the Content-Disposition or Content-Type Headers are not set or encoded properly by the server. 

Why It Happens in Chrome (but not Firefox, Edge, Brave): Chrome is more strict with filename encoding and may mishandle characters if the server doesn't specify them in a way Chrome expects (especially with non-ASCII characters or spaces). Brave, while Chromium-based, sometimes handles downloads differently due to privacy features. Firefox and Edge are more forgiving and apply their own logic to fix these discrepancies.

Since the site is running Drupal, here’s how you (or your web team) can try to resolve this using these workarounds: 

Set Proper Content-Disposition Headers: Ensure the server sets this header when serving PDFs: Content-Disposition: attachment; filename="GAL_Guide.pdf"

Avoid Double URL Encoding: Drupal sometimes encodes file names multiple times. Or apply a hook to clean the filename output: 

function mymodule_file_download($uri) {
  $filename = basename($uri);
  return [
    'Content-Type' => 'application/pdf',
    'Content-Disposition' => 'attachment; filename="' . rawurldecode($filename) . '"'
  ];
}

Use Clean, ASCII-Compatible Filenames: When possible, remove characters like brackets [ ], % symbols, or encoded underscores from uploaded file names.

Workaround for Users: Until the server-side fix is in place, Chrome users can: Right-click the PDF link and choose "Save link as...", which often corrects the filename. Or use Firefox/Edge if they need more consistent naming for now.

As suggested earlier, you should contact the Chrome support team and see if they can assist you with this. 

Note: The steps above are suggestions and workarounds; you may need to modify the code or customize the steps according to your requirements and the machine environment.

I hope this helps.

Thanks,

Anand Sri.