After Effects won't render

I was having the exact same problem.
I found it was a problem with how After Effects handles Multiprocessing.
Something must have happened in a recent update as this problem came on suddenly.
I figured out a work around until they patch this.

- Go to your Preferences in After Effects.
- In the Memory & Multiprocessing category there is a section on After Effects Multiprocessing.
- Uncheck "Render Multiple Frames Simultaneously"

- That's it

Unfortunately, until there is an official fix for this After Effects won't be able to take advantage of Multiprocessing.

I know this is almost a month late, but I thought you or someone who stumbles on this might like somewhat of an answer.