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.

Internet Explorer also supported the once-popular ActiveX plug-ins, which enabled it to open types of files not normally supported by browsers. Many old sites relied on ActiveX in order to function.

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.