Colorado regulators fined human cloud firm Uber $8.9 million yesterday for allowing individuals to drive who had disqualifying criminal or motor vehicle offenses, or did not have valid licenses.

The Colorado Public Utilities Commission issued the civil penalty assessment notice to Uber’s parent company, Rasier LLC.

Uber said in a statement that it had uncovered the error and taken steps to correct it.

“We recently discovered a process error that was inconsistent with Colorado’s ridesharing regulations and proactively notified the Colorado Public Utilities Commission,” an Uber spokesperson said in a statement. “This error affected a small number of drivers and we immediately took corrective action. Per Uber safety policies and Colorado state regulations, drivers with access to the Uber app must undergo a nationally accredited third-party background screening. We will continue to work closely with the CPUC to enable access to safe, reliable transportation options for all Coloradans.”

The violations involve 57 Uber drivers over the last year and a half who should not have been permitted to drive for the company, according to the Colorado Department of Regulatory Agencies. The company was cited $2,500 a day for each day a disqualified driver was found to have worked.

Colorado launched an investigation earlier this year after a referral from the Vail Police Department about an Uber driver accused of assaulting a passenger.

“PUC staff was able to find felony convictions that the company’s background checks failed to find, demonstrating that the company’s background checks are inadequate,” PUC Director Doug Dean said. “In other cases, we could not confirm criminal background checks were even conducted by Uber.”

Among the findings of the investigation were 12 drivers with felony convictions; 17 drivers with major moving vehicle violations; three drivers with interlock driver’s licenses, which are required after recent drunk driving convictions; and 63 drivers with driver’s license issues. Uber’s background checks also failed to identify a number of aliases used by drivers.

Colorado law requires a transportation network company, or TNC, to perform a criminal history record check prior to allowing a person to act as a driver for the company. The company must also obtain and review a driving history report for individuals before they are allowed to drive. Drivers must have a valid driver’s license. TNCs are required to disqualify drivers who have been convicted of specific offenses listed in the statute — such as felony convictions, alcohol or drug-related driving offenses, unlawful sexual offenses and major moving vehicle violations.

Under PUC rules, Uber can resolve the case by paying 50% of the civil penalty assessment notice amount within 10 days, or request a hearing before an administrative law judge.

Drivers’ backgrounds may become less important in the future; Volvo Cars on Monday announced it signed a framework agreement to sell Uber 24,000 autonomous driving compatible base vehicles between 2019 and 2021.

“This new agreement puts us on a path toward mass-produced, self-driving vehicles at scale,” Jeff Miller, Uber’s head of auto alliances, told Bloomberg News. “The more people working on the problem, we’ll get there faster and with better, safer, more reliable systems.”