Created attachment 104532 [details] error log All the frames are exported correctly in PNG but cannot be rendered into a video or gif. This has been the case every time I try to render animation from any of my Krita files. Thank you for your help.
I cannot test on OSX, but it seems like the a temporary file for a progress indication cannot be created. If the file cannot be created, then QTemporaryFile returns an empty string (which is seen in the log). Do you have any special settings for the temporary files on OSX? You can use "Console" OSX application to get more debug output from Krita. If you manage to attach a Krita log generated while rendering, I can try to resolve the issue.
*** Bug 371553 has been marked as a duplicate of this bug. ***
This works for me with 4.0 beta 1.