It's not very frequent that this terminal rendering error comes into the support or happens at all but it does happen and it will leave a few people scratching there heads.
Well, no need to worry at all. This error is very minor and it will show up because a user has somehow overlooked at what command they are sending. It really only takes one character to be out of place.
Below is the example we usually see.
Render -r -mr file.ma
If you look carefully, there is a extra hyphen being used. To fix this just remove the hyphen just before "mr". The "-r" is the only valid flag in the above example and the render will fail because what follows is not a valid string to go with the flag.
So the correct command would be.
Render -r mr file.ma
small user error but does get missed by some folks.