An upbeat Hosni Mubarak was wheeled into a Cairo courtroom for his retrial for alleged complicity in the killing of demonstrators during the 2011 revolt that ousted him.
But the session quickly ended when the judge recused himself.
The 84-year-old former Egyptian president waved from his wheelchair inside the courtroom cage, having been airlifted to the court from a Cairo hospital.
His two sons Alaa and Gamal and his former interior minister Habib al-Adly, currently held in prison for separate cases, were also in the courtroom cage.
Mubarak had not been seen in public since his initial conviction in June 2012. Unconfirmed reports have emerged several times in the past year suggesting that he was on the brink of death.
Judge Mostafa Hassan recused himself and referred the new case to an appeals court to select a new judge to oversee the trial. He did not specify the conflict of interest behind the decision.
Hassan caused an uproar in October among Egyptian political activists when he ordered the acquittals of 25 Mubarak loyalists who had been accused of organising an attack in which assailants on horses and camels stormed Tahrir Square during the 18-day revolt.
Mubarak's retrial was granted by an appeals court that overturned his life sentence in January, citing shoddy procedures. He has remained in custody since, spending some time in a prison hospital before being transferred to a military one.
If convicted again, the life sentence passed against Mubarak and el-Adly would be upheld. They could also have their sentence reduced or even be acquitted.