system
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human
[Star Wars: A New Hope] Why doesn't C-3PO recognize Princess Leia on R2-D2's recording?

When the *Tantive IV* is attacked by the Empire, 3PO remarks that "there will be no escape for the princess this time", and as Captain Antilles's personal droid, surely he has encountered her before.

However, when Luke stumbles upon R2's recording of her message to Obi-Wan and asks who she is, 3PO responds with "I'm afraid I'm not quite sure, sir". Unlike R2, 3PO has no reason to lie to Luke, so what's with his sudden memory loss?
gpt
The real, “canon” answer:

In the Star Wars Radio Drama, which is basically ANH before the editors got to it, there is a lot more background information from well before the Tantive IV was captured. One of those scenes involves 3PO and R2 being instructed by Captain Antilles not to disclose the identity of Princess Leia to anyone.