A bug discovered in the recently launched Android 8.0 Oreo spends users' mobile data allowance, even when the phone's mobile WiFi connection is enabled.

Smartphones can connect to the Internet in two ways. Via a local access point or router (WiFi connection) or by using the mobile carrier's network (mobile data connection).

Most users enable one or the other option when connecting online. Some users enable both in the hopes of having a continuous Internet connection at all times.

By default, the Android OS will prioritize the WiFi connection over mobile data, as to avoid incurring extra costs on the user's mobile plan.

Oreo bug prioritizes mobile data via WiFi connections

Because of a recently discovered bug, Android Oreo — the latest Android version released two weeks ago — does the opposite and uses mobile data for Internet connections, even when WiFi is enabled.

The bug came to light after several users who recently updated to Google's latest Android release had the unpleasant surprise of finding out their mobile data allowance had faded away out of the blue.

"After updating to Oreo last night, I received a huge spike in data usage, all the while being connected to WiFi," said one user who posted about the bug on Reddit.

"That might explain why I have 6gb of data usage 2/3 of the way through my cycle," another disgruntled user responded. "That's pretty bad on Google's part. They're directly ruining people's bills."

Google working on a fix

A Google spokesperson told Bleeping Computer the company is aware of the issue and is working on a fix.

Not that many users have updated to Android Oreo at the time of writing, and most users are Nexus owners. If Google rolls out a patch, they will receive it right away.

Users on other types of devices might have to update manually once a patch is out, as most mobile carriers are quite late when it comes to delivering Android updates.

Android Oreo users who are used to enabling both Internet connection types should disable mobile data and use one connection at a time to avoid extra costs on their mobile plan.