Faraz Shere knew exactly what he would do for the biggest holiday on the Muslim calendar. The night before the feast-day of Eid-ul-Fitr, he and his family would stroll among the brightly lit shops of Lucknow, meeting friends and sampling sweets that filled alleyways with the scent of honey and almonds.
Then something unexpected happened.
At 3 a.m. Tuesday, the mullahs of Lucknow pronounced from loudspeakers that today was Eid. Mr. Shere had to drag his disbelieving mother out of bed and onto the rooftop to hear the announcement.
"It's a lie," she yelped, panic-stricken.
Like many of India's 138 million Muslims, the Sheres thought the feast day to end the month-long Ramadan fast was Wednesday. So preparations were not complete.
The confusion is a story of tradition versus Internet, of moon committees and clerical politics. But most of all, it is a story of millions who watched the most cherished night of the year disappear from the calendar. "I am very disappointed because I missed my friends and I missed that charm," says Shere.
According to Islamic law, the Ramadan fasts end when imams see the first new moon of the new month. It is an event steeped in history: imams have created moon committees to promulgate word of the sighting. Yet in an Internet age, the date of the new moon is no great mystery. Calculations forecast that it would rise Tuesday night, making the following day Eid. So many Muslims planned accordingly.
Iqbal Ahemed Khan asked for Wednesday off so he could linger after morning prayers to hand out money and sweets to children. But Tuesday, after midnight, the mosque loudspeaker in his Delhi neighborhood proclaimed it was Eid, and Mr. Khan had to go to work after his prayers.
Beneath the change is a rebellion against the tyranny of astronomical certitude. "While it was announced earlier, on the basis of scientific prediction, that Eid would fall on the 25th, since it was not according to [Islamic law], we didn't agree with the determination," says Maulana Khalid Rashid, an imam in Lucknow. "The date for Eid is decided only once the moon is sighted."
For this reason, it is not unusual for there to be disagreements about the date for Eid. Saudi Arabia generally celebrates Eid a day ahead of India. Pakistan often sets aside three days for local discrepancies. This year, the same thing has happened here. In one southern state, Eid was celebrated on Monday.
In other parts of the country, it was on Wednesday as expected. But in Lucknow, as in Delhi, the early sighting of the new moon happened too late to let Muslims enjoy Eid eve.
The result, in some cases, was chaos.
Shere raced through his house, waking up family members, exhorting them to start their holiday cooking and cleaning in the middle of the night. "We were not exactly prepared for that," he says. "At 3 o'clock, everybody was doing the preparation."
There was, he adds, no small amount of shouting. In the end, after the hours of preparation followed by morning prayers, he ended up sleeping through much of Eid.
For Khan, though, things turned out better. He was able to break the fast with his family Tuesday afternoon, and he passed out sweets to children in the evening.
"In spite of all the confusion, we managed to celebrate Eid very nicely," he says.
• Saurabh Joshi contributed to this report.