Google on Monday said it has decided to shut down its social media network, Google+. Alphabet Inc, Google’s parent company, said about 5,00,000 Google+ accounts were potentially affected by a bug that may have exposed their data to external developers.

A report in the Wall Street Journal said the company knew about the matter in March but did not disclose it, because it did not want to expose itself to scrutiny by the regulator. A software glitch on Google+ gave outside developers potential access to private data between 2015 and March 2018, when it was finally fixed.

In a statement, Google said it believed the problem was not serious enough to inform the public. “Our Privacy and Data Protection Office reviewed this issue, looking at the type of data involved, whether we could accurately identify the users to inform, whether there was any evidence of misuse, and whether there were any actions a developer or user could take in response,” it said. “None of these thresholds were met here.”

Shares of Alphabet Inc fell over 1% on the NASDAQ after the news of Google+ shutting down was made public.