Russia postponed the planned debut launch of the Angara rocket, its first new design of space vehicle since the Soviet era, just minutes before it was due to blast off on Friday.
A senior military commander gave no reason for the delay, but a commentator on Russian state television said the launch had been put back for 24 hours until Saturday.
More than two decades in the making, the Angara is a centerpiece of President Vladimir Putin's plan to reform the once-pioneering space industry and launch satellites from a new space port being built in Russia's far east.
"The automatic system aborted the launch during the countdown," Alexander Golovko, commander of Russia's Air and Space Defense Forces, told Putin moments before the launch was due to go ahead.
Putin, who had been poised to watch the rocket's inaugural flight from the northern military Plesetsk cosmodrome via video link from the Kremlin, ordered his generals to report on the cause of the delay within an hour.
The development of the Angara - the first rocket entirely designed and built within post-Soviet Russia's borders - is intended to break a reliance on the Baikonur launch pad Russia leases from Kazakhstan and foreign suppliers.
It's maiden flight is seen as test Russia's ability to turn around a once-pioneering space industry that is struggling to recover from a brain drain and years of budget curbs.