My team at work identified an issue that we developed a Sharepoint Online site and when testing it on our company's browsers, most of the content doesn't appear. This includes the custom modules developed using the Sharepoint Framework. We identified that the issue is related to the browser version that we have which is 45.3. This browser version doesn't seem to be able to read the new framework somehow as most of the functions are grayed out when inspected in source window. The reason we are using an old version is because there are some internal applications that are dependent of that version.

So I'm interested to know if this version is possible to be backwards compatible with Firefox ESR 45.3 or will we have to inevitably upgrade the browser?3