Accidental free parking in downtown Minneapolis finally got the boot Wednesday.

City crews were able to get 138 on-street pay stations back in service, rebooting each one after they unexpectedly went out of service Tuesday.

The problem surfaced after a software update to the parking meter system Monday night, providing a "free parking" opportunity for motorists winning a spot assigned to an inoperable multi-space payment station.

A short-term meter amnesty was implemented as city crews worked to repair the stations.

The problem was concentrated at pay stations in an area bounded by Hennepin Avenue on the west to 5th Avenue S. on the east, as well as those on either side of Hennepin Avenue around Loring Park.

City officials said they are working with the manufacturer, Sweden-based Cale, to determine what went wrong.

The pay stations, which take debit and credit cards as well as cash, started showing up on the city's curbside landscape in November 2010, steadily pushing aside more of the single-space, coin-only meters that have stood on curbs nationwide for decades.

The solar-powered stations are more convenient for motorists and have produced a sharp jump in revenue for Minneapolis since they were installed.

They now total more than 600 in Minneapolis.

More than half of the city's parking space transactions have been by credit or debit card.