I'm getting "After Effects Error: Photoshop File format error 1. (45::35)" in AE CS 6 with .IFF's from Maya. I know this is nothing new, this problem has been around for a loooooong time.
We like here at ABC like .IFF since it's native to Maya and a small file with alpha.
Close and open AE and it works for a while then the error appears, rather than me doing a work around and converting to another format, my question is: When do you think Adobe will have a solution?
The better question actually is: When will Autodesk stop "enhancing" the IFF format? There really is two sides to the equation and as long as Autodesk implement undocumented changes (including trivial stuff like incrementing the IFF version number in the metadata), any other company can only paly catch-up. Also the format has this odd "quality" where byte errors do not necessarily affect the visible data, so rendering errors may not actualyl show up unless you open the files in anotehr program. I understand your rationale for using it, but it really is not the best format for heterogenous workflows involving apps from different vendors. TIFFs are so much nicer...
This is a new bug in CC. I updated to CC and immediately started seeing this. Make sure PhotoShop is closed (probably other CC apps too) and there shold be no problem. This is not an IFF file format issue based on an autodesk change. I open old projects and same thing happens. Looks like PS steals a resource that is needed to read the IFF files. Downloading the latest update now to see if it has been fixed.