Check-in systems at various airports faced issues on Wednesday morning due to a system outage, according to a source.
The source added that some flights have been delayed due to the issues.
"Microsoft Windows reports major service outages globally. IT services/ check in systems at airports are impacted," as per a message for the passengers at the Varanasi airport.
According to the message, airlines have implemented manual check in and boarding procedures.
At least four airlines -- IndiGo, SpiceJet, Akasa Air and Air India Express -- have been affected, it said.
There were no immediate comments from Microsoft or from the airlines.
"Some domestic airlines are currently experiencing operational challenges, which may lead to delays or schedule challenges.
"Our on-ground teams are diligently working with all stakeholders to ensure a seamless and efficient passenger experience," DIAL said in a post on X at 7.40 am.
Specific details could not be immediately ascertained.