Nobody can tell you anything without proper system info or other technical details like version of AE and what's contained in the projects just as well as possibly the exact command strings and settings used in both cases. This could simply be a typo, but then again this could also indicate a permissions problem e.g. with some animation preset and associated (pseudo-)effects or a script.
I'm running the latest version of AE and the problem is occuring on 2 different systems.
The only 3rd party plugins in the project are trapcode stroke and soundkeys
The problem presents when using the basic "aerender -project c:\project.aep" command
There are already comps setup to render in the queue and the project has been saved and closed.
Basically, I can't even find any information on what that error code MEANS, let alone how to fix the issue.
Start by removing the comps from the RQ and explicitly calling them and setting the output name in the command string. I have a hunch that this has something to do with the automatic naming template stuff introduced in CC and the code is parsing some name wrongly. Similar issues have been reported before.
I think you might be right, I'm using templates that are set on one machine and running aerender on a separate machine which doesn't have the same template so i'll give it a go in the morning and see how it runs.