First----have a meeting of the minds with your son so that you both clearly understand whether he filed incorrectly and if you can claim him as your dependent. You say he finished college --- how old was he at the end of 2020? It matters.
IRS interview to help determine who can be claimed:
https://www.irs.gov/help/ita/who-can-i-claim-as-a-dependent
https://ttlc.intuit.com/questions/3113432-who-can-i-claim-as-my-dependent
For your son:
https://ttlc.intuit.com/community/dependents/help/when-do-i-have-to-answer-yes-to-being-claimed-as-a...
If it turns out that your son made a mistake and you can claim him as a dependent on your own tax return:
MY DEPENDENT SAID HE COULD NOT BE CLAIMED
Your dependent filed a return without saying he could be claimed on your return and your return was rejected? AFTER his return has been fully processed and he has received his refund, he has to file an amended return that says he can be claimed as a dependent on someone else’s return. Amended returns must be prepared on a Form 1040X— It takes the IRS about six months to process an amended return.
Meanwhile, since your e-filed return has been rejected, you now have to print and mail it in to the IRS. You will not be able to e-file. You do not have to wait for your dependent’s amended return to be processed. Remember that when you mail a return, you need to include copies of your W-2, etc. with your return. Use a mailing service like certified mail that will track it so you will know that the IRS received it.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
