When using robocopy windows utility, what flags do I set so that robocopy aborts on the very first error it sees, similar to xcopy /dry command?

I need to mirror two dirs, and on occasion some files would be locked. I do not want robocopy to continue trying to copy files, or override the files that are not locked - rather the very first error should stop the whole copy process.

UPDATE:

I already have the /R set to 0 - unfortunately that it only applies to a single file, NOT to the whole copying process. Hence, the first file is ignored (instead of stopping the copying), but subsequent files are copied.