Do you mean a 1095A----the form for having health insurance from healthcare.gov? Did you have "Obamacare" or Affordable Care Act or Marketplace health insurance? If so, you need your 1095A.
If you are getting a rejection for 1095-A then this indicates that IRS records show your son is covered by a marketplace health insurance plan. When that's the case, the information form 1095-A must be entered on the tax return even if it is also entered on another return (such as the parent).
The 1095-A premiums and credits can then be allocated at 0% so that it doesn't materially affect the return but without this information, the IRS will not accept the return in the e-file system.
If your son was not covered by a marketplace plan, you'll need to print and mail his return as there isn't a way to overcome this rejection without a 1095-A information.