OS? AE version? Comp info? Render Settings? Output Module Settings? Codecs used? Without info We can't help. Include version numbers down to the last decimal point.
AE CC, Windows 7, 64-bit
Attempting to export an animated Illustrator file, 8bpc, H.264 Codec, no audio
Render Settings are "Best"
I hope that helps!
Is your CC up to date (12.What?) Is Windows 7 up to date?
Comp size? 3d? You're still being stingy with the details. This could be anything from MP errors, memory and cache settings, comp size, incompatible plug-in.
This looks like a Quicktime error where you comp size or render settings do not match the required specs of the chosen H.264 preset... Either way, as Rick said, we need to know a lot more...
I just ran into this error when I tried importing an Illustrator file. No restarting or reinstalling worked for After Effects CC(2014) on my Mac Book. What however helped is exporting that Illustrator file into a .psd and importing that file instead. It worked fine after.
Additionally, I was importing Illustrator files earlier this morning without a problem.
I had the same problem, that's because you imported your A.I layers as footage.
It seems the bug desappear when you chose in the import box "import as comp layer".
I hope it will help ;-)