The IRS uses reference code 9001 to indicate a "
Systemic error/issue". In other words, it's likely not a problem with
your return. Take a deep breath, wait a day or two, then try again. The IRS won't start processing your return until at least January 28 anyway, even if they said it was accepted.
Yes, this means that the 9001 may not go away until we are closer to January 28th.