It seems there was a service disruption with Gmail this morning, however, users say, it seems to be working fine now.

Although the issue has not been recognised by Google on their website, people on Twitter complained that the service had been down for over an hour.
Gmail server down
Many users reported receiving a 502 error while trying to access any Google service.

Tweets from users reporting the error seem to indicate that it is users from India who are facing a problem. There is still no word from Google on its official communication channels regarding the glitch. However the head of Mumbai Financial Times, James Crabtree said he had been told that the reason for the outage was a power cut in Gurgaon.

“502. That’s an error. The server encountered a temporary error and could not complete your request. Please try again in 30 seconds. That’s all we know,” reads the message on the error page.
502 errors usually happen due to poor IP communication between servers. There have been a number of previous occasions when Google users have encountered a similar error, but this seems to be the first time when its has affected a multitude of Google services.

Recently, in April, Gmail and Google Drive was down for sometime.

A support website downrightnow which monitors the status of web services, combining user reports and official announcements to tell you when there’s service trouble also showed that the Gmail is service is down. However, it says the service is working fine now.