When you save in AE, you're saving the project file -- which inclues all your work in the comp -- but you can't save the comp itself to a media file. It doesn't work that way. You have to export or use the AE Render Queue.
Show a screenshot of the exact error message.
My guess is that you're trying to save to a location where you don't have write permission.
Open AE, before you import anything save the project to the desktop by seleting File>Save
If that doesn't work give us your system specs, OS and AE version.
Thanks for your suggestions. I have tried the above and it doesn't work. I think it may be because my mac is too old it is a 2x2.66 dual core with 4GB memory and is probably 6 years old. I am running CS6. However, I haven't had problems with either flash or premiere pro.
GO TO THE FOLDER AND RIGHT CLICK(MAC):
CLICK GET INFO, AND UNLOCK THE LOCK ON THE BOTTOM RIGHT CORNER. MAKE SURE ALL THE PROJ FILES SAY THAT THEY'RE ALL WRITABLE & READABLE.
- IF THIS DOESN'T WORK, FIND OUT IF YOU CHANGED YOUR PROJ FILE NAME. THIS WAS MY PROBLEM. SO JUST EXIT OUT OF AFTER EFFECTS AND CLICK ON THE FILE THAT'S LIKE:
AEtemp-4F19D- OR SOMETHING. HOPE I HELPED YOU
I just sold my 2013 MacPro and moved over to a Windows machine. I've been running the new machine for less than a week and as soon as I started working in After Effects I experienced this exact same issue, but only when rendering TIFF sequences to an external Pegasus2 Thunderbolt RAID (The machine has a Thunderbolt 3 motherboard and I connect everything via thunderbolt 3 to 2 adapter).
AE renders TIFF sequences to my second local SSD just fine but I use that as a scratch disk and would prefer to render to my project location. I realize this may be an issue with Thunderbolt, but JPEG, PNG and Photoshop sequences all seem to render fine.This happens in both AE 2017 and 2015.5 and I imagine that means the same thing will happen in earlier versions, although I haven't tested it.
I believe the permissions are set correctly to read/write on the RAID, although being rather new to Windows, I guess there's a chance I may have made a mistake. Anyway I would really like to get this to work, so any help would be greatly appreciated.
im using a pretty cluttered mac myself. just fixed this same error by cleaning up my application cache, and thus storage (not sure if storage made a difference. my drive was @ 99%). you might find the application "disk doctor" useful.