Render stops after 1 frame. "Render error (Permission denied) cannot save: '0001.png'"

For some reason today I can no longer render more than 1 frame at a time. I was able to just fine yesterday. After successfully rendering the first frame, render stops and I get this error message:

Render error (Permission denied) cannot save: ‘0001.png’

I tried saving output to local drive instead of server but no luck.

I am using the “File output” node in the compositing node editor, and NOT using the render settings output path. I just tried putting something in the output path and leaving the composite nodes untouched, and now it renders fine but renders each frame twice (once for the File Output node, and once for the render settings output path.)

Why would I get this error?

I realize I’ve found a workaround where I just have to delete the extra renders, but I want to get to the bottom of this problem. 😉

Thanks!