PDF Files will not open in Internet Explorer 1. Press Windows Key + R combination, type put Regedt32.exe in Run dialog box and hit Enter to open the Registry Editor.

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.

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.