Due a large dust storm that occurred within the area near the rover in June 2018, Opportunity was forced into hibernation mode. And within the past 7 months, all of NASA's attempt to reestablish contact with the rover has failed and on February 13, 2019, NASA officially declared the Opportunity mission as complete.
The last photo taken by Opportunity during the dust storm, note that this was taken during the Martian day time:
The Opportunity and its twin rover Spirit were launched into space in the middle of 2003 and landed on Mars in January the next year. They were expected to last for only 90 days, instead they lasted well over that. Spirit lasted until 2010 when it suffered a power failure, but Opportunity kept on going alone until it was joined by Curiosity in 2012. The rover's greatest feat was finding proof that water was present on the surface of primordial Mars.
An era of Mars exploration has come to an end. Opportunity was not the first rover on Mars, and it certainly won't be the last. 3 more rovers from the United States, China, and Europe are expected to join lone Curiosity by 2021. The contributions made by Opportunity won't be forgotten, and may it rest peacefully on Mars.