The qualifying child reported on your tax return must have the correct full name, SSN, and DOB listed. These fields must match what is currently on file with the IRS e-file database and Social Security Administration.
Fix #1: Sign into your PriorTax account to doublecheck that each child's name, SSN and DOB are correctly reported. If not, update as per the instructions shown on your rejection status page.
Fix #2: If the information you provided seems to be correctly entered to the best of your knowledge, then you may need to paperfile your tax return for this year and contact the Social Security Administration as soon as possible to update this information.