Clipper is sending out thousands of notifications to transit riders that it will be collecting missed payments due to problems with the system, according to the San Francisco Chronicle.

Nearly 8,000 uncollected transactions dating as far back as 2010 will receive e-mailed notices through the beginning of September alerting that their accounts will be charged for missed payments.

Most of the transactions involved customers whose automatic downloads occurred while riding a bus, said John Goodwin, a spokesman for the Metropolitan Transportation Commission, which oversees Clipper. Passengers tagged their Clipper cards, and their accounts were replenished, but when the bus returned to the yard, the data were not uploaded to the Clipper computers.

It’s not clear how many customers will be affected by the glitch in the Clipper system, but Clipper failed to collect some $231,000.

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