Jeff Jones has resigned from his post as the president of cab-hailing service Uber, Reutersreported on Monday. He had joined the company only seven months ago and was widely expected to be made chief operating officer, the company’s second-in-command after Chief Executive Travis Kalanick.

The reason for his departure is unknown. “We want to thank Jeff for his six months at the company and wish him all the best,” is all that an official statement read. This comes after a series of controversies and high-profile resignations in the company.

While senior executive Ed Baker left the company earlier this month, engineering executive Amit Singhal was asked to step down from his post in February after sexual harassment allegations against him from his previous stint at Alphabet Inc.

In February, a former Uber employee alleged sexual harassment at workplace in a blog post and accused the company management of inaction. Kalanick was soon after caught on camera fighting with an Uber driver about rate cuts and pay. Adding to Uber’s woes, Alphabet recently sued the company for allegedly “stealing” its designs for autonomous cars.