About This Answer
Is a bodhisatta enlightened, and could someone have made a bodhisatta vow in a past life without knowing it? The answer describes the bodhisatta as a being practising for Buddhahood. Many make this determination, but most abandon it along the way.
While such a vow stands, its power prevents mindfulness and discernment from letting go of the kilesas, the defilements. The person keeps developing spiritual perfections but does not realise the Dhamma. Ajahn Dtun's reply notes it is quite possible that someone present made such a vow in a former life and now, wishing to end suffering, finds that however hard they practise they cannot attain.
The remedy is to make a new resolution when the mind is peaceful: that any vows made in the past, remembered or not, be null and void, and that one now wishes to go beyond suffering. Made with a peaceful mind, the new determination can erase the old one and take effect.