A writ of coram nobis asks the Appeals Court to address new facts not presented at trial. In Virginia you can file a motion for a Writ of Actual Innocence with the Court of Appeals. There are a few different grounds for filing such a motion and you should contact an attorney to assist you with preparing the motion. Please look at the following link for more information from the Court of Appeals
It still exists.
§ 8.01-677. Errors corrected on motion instead of writ of error coram vobis.
For any clerical error or error in fact for which a judgment may be reversed or corrected on writ of error coram vobis, the same may be reversed or corrected on motion, after reasonable notice, by the court.
However, the Supreme Cour of Virginia has held that what was once a broad common law remedial measure allowing the Courts to correct an injustice or to right a wrong, it is been restricted to what is in 8.01-677.
If the motion is due to improper advice or no advice as to immigration consequences as a plea, corum nobis (or vobis) is not available.
This appears to be the same question from another post. Here is my answer:
A writ of coram nobis (or "coram vobis," which is the same thing) is limited to claims of "clerical error or error in fact."
To answer your specific question, it has not been abolished in Virginia, but it has been greatly limited by case law and statute. It is not the same thing as a Writ of Actual Innocence or a Habeas Petition. For instance, coram nobis CANNOT be used to challenge the validity of a guilty plea or to allege ineffective assistance of counsel. See Va Code 8.01-677; Commonwealth v. Morris, 281 Va. 70, 705 S.E.2d 503 (2011).
Therefore, your son should use the appropriate action for whatever he wants to correct or challenge. Coram nobis is so limited that my best guess would be that he needs to use a different method.