I wanted to post about this issue just in case someone else comes across it, so they don't have to spend their time with debugging it.
The Problem:
Yesterday I had the issue that when rendering an IPR preview of my scene it worked completely fine.
Upon exporting it either over the render preview or with a batch/sequence render to an .exr file the file was exported and seemed fine from the outside, but when opening it the .exr file was corrupted and Photoshop was unable to open it.
After a lot of trial and error I figured out that it was connected to the AOVs as when all are turned off the project rendered just fine.
The Solution:
As it turns out, when you render a file with an AOV pass that is turned off (as for example with this project the transmission and SSS Samples were set to 0), maya still renders the file, but when saving it corrupts the .exr.
So in case it helps someone turn off your layers or remove them fully if you set the related samples to 0.
