Hello,

If your downloaded PDFs still won't open, there could be a few common problems affecting you. First, make sure you have installed a reader that supports PDF files and is compatible with it, such as Adobe Acrobat Reader or your system's built-in PDF viewer. Check that the file is not corrupted by redownloading from the original source. This can also occur if the download failed, and the file is incomplete, so it cannot open.

Ensure the file is not stored in the forbidden folder for mobile users. Clear cache or storage if your PDF app on your device has a problem. Lastly, ensure that the device supports the version of your PDF you are trying to access. In case none of that works, update or reinstall your PDF reader application.