iPhones can't open greyed files. When an iPhone can't open a specific file type, it greys out the file in your selector, making it unclickable. This will happen if you don't have the right viewing software downloaded to your device. The most common type of greyed-out file on iPhone is a PDF.
Source : https://www.adobe.com/acrobat/hub/why-pdf-files-are-grey-iphone.html
Sometimes, email attachments may not open because they are infected with viruses or malware that can harm your device or data. This can happen if the sender's email account or device is compromised, or if the attachment is from an unknown or suspicious source.Sep 12, 2023
Source : https://www.linkedin.com/advice/3/how-can-you-handle-email-attachments-wont-open-communication-advice
Downloads.On your Android phone or tablet, open the Chrome app .At the top right, tap More. Downloads. If your address bar is at the bottom, swipe up on the address bar. Tap Downloads .To share a file, tap More Share. To share more than one file, touch and hold the files you want to share, then tap Share .
Source : https://support.google.com/chrome/answer/95759?hl=en&co=GENIE.Platform%3DAndroid
If you can't open a file, it could be because: You don't have permission. You're signed in to a Google Account that doesn't have access. The correct app isn't installed on your Android device.
Source : https://support.google.com/docs/answer/6211862?hl=en-ph&ref_topic=9110468
To view and delete the downloads history in Safari, please the steps below: Open the browser. Click on the View tab in the upper menu and select Show Downloads. Or, you can directly click the Show Downloads button in the Safari toolbar.Jul 18, 2023
Source : https://www.partitionwizard.com/partitionmanager/downloads-history.html
Clear Browser Cache and Cookies An outdated or corrupted browser cache is a common reason for elements on a web page, including PDFs, to not display correctly. Clearing your browser cache should prompt your browser to download up to date content and hopefully fix the issue with rendering your PDFs properly.
Source : https://www.uhd.edu/computing/training-lms/troubleshooting-chrome-pdf-viewer.aspx