Well, some users have reported facing a problem that, whenever they try to download and open a PDF file, Internet Explorer will not open PDF files. Sometimes IE just hangs while downloading PDF files.

How to Open a PDF With Reader & Internet Explorer. Adobe's portable document format (PDF) has become a standard for exchanging and distributing documents. PDF files look like the original document ...

In case you're one of the people who's been trying to open a PDF via Internet Explorer 11 to no avail, fear not: Microsoft heard you and has addressed the problem with its KB5004760 update.