Does forgetting the intention for 'Umrah at the Miqat, despite leaving home with the intention of performing 'Umrah, invalidate the 'Umrah?

Ihram is the intention to enter into thek rites. And whoever does not intend to enter into the rites has not entered into ihram; rather, he remains in a state of permissibility (halal), due to the Prophet's (peace be upon him) saying: "Deeds are but by intentions."