I've recently made the switch to Firefox last month and was trying to view a PDF embedded inline on a site (Canvas, commonly used in schools and universities), but kept getting a blank box. I had to download the file to view it- I couldn't just preview it. I'm aware that "previewing" or "opening" PDFs without choosing to save them actually just saved them to a temp folder locally which the system would delete eventually on its own, and this new change from version 98+ supposedly "optimizes" the download process because "Firefox no longer saves files to a temporary folder because of the downsides to saving files in a location that is hard to discover." Downsides? What downsides??? '''Removing that feature quite literally does the opposite of optimizing when the average user, and in fact all users, benefit from being able to preview PDFs by keeping them in a temp folder.''' If we wanted to download something, we would '''choose to save the file where we want it to be'''. You're literally presenting "save file" and "open file" as if they're two different choices, when "open file" is really just "save file, and then we open it for you, and you have to manually delete it yourself later!". This is objectively a downgrade in every way. There's no optimization here. I realize that me as just one person asking for this will fall on deaf ears, but I have to try. '''Please bring back the option to preview files by automatically saving them to a temp folder without me having to set my default download folder for ALL files as a temp folder. ''' Please think about the situation of someone like a teacher who needs to mark 40 students' PDF homework submissions in Canvas, which lets you quickly change between inline previews within the site of each PDF with its grading UI on the side, making it convenient for them to grade. With this change they either have to download 40 PDFs onto their hard drive, or go back to using Chrome, where the PDF.js extension (the very same PDF viewer that's built into Firefox and backed by Mozilla?!) actually will let them preview the temp files, no problem. And I'm not even teaching right now, I'm just a student who fell into this rabbit hole because I wanted to do my homework and all the PDFs are blank boxes in Firefox while they appear just fine on Chrome. I really want to be using Firefox full time. I really do! But by taking away this very useful feature, you're literally forcing my hand into using Chrome again.