I received reject. Itice R0000-507-01, how can I see which dependent they are questioning? I been claiming my child all this time until now for 19 years?

This usually means that someone else has already claimed your dependent. They may have even claimed themselves. For confidentiality reasons, the IRS is unable to disclose who that person is. For more information please click the link below.

TurboTax Online instructions for E-file reject R00 ...

See if this post helps for which ssn was rejected

https://ttlc.intuit.com/community/after-you-file/discussion/how-do-i-find-out-which-ss-is-already-used/00/788671

The -01 probably means the first dependent listed.