Recently in MT3.16 Category

In a nutshell, in MT3.16 when you upload a file and select the file to be displayed as a "popup", the resulting link to that popup returns an error. (the slash before the filename is parsed as its html hex entity %2f rather than / ). This is a known issue in 3.16 and there are a couple temporary fixes floating around. I employed the hack described at danandsherree.com. An alternative (unofficial) fix can be found on the MT Support Forum. The latter changes subroutines other than upload_file, thus I prefer the one from danandsherree since it addresses only the upload subroutine -- it's working fine for me.

1)  copy main index template from

to 2)  in individual archive template paste (what you just copied above), replacing from to 3)  cut from beneath/end of "FORGET INFO" code and paste under/at end of (FINISH THIS THOUGHT! brain fart... sorry!)

That is all fine and dandy as long as you have comments open. If comments are closed you need to clear the floats or your 3 columns will be differing lengths. Not a pretty sight! So...
4)  paste this code:

just above these closing tags near bottom of page (using tags for 3.1x or earlier):

or if you're using 3.2 tags clear goes BETWEEN these tags like this:

This is what worked for me. Hope it works for you.