The issues identified by the Gambling Commission included a fault within the lottery’s mobile app and the publication of an incomplete list of Lotto prizes online.
It said players using the National Lottery mobile app may have been presented with an incorrect “non-winning” message when checking a winning ticket using the manual results checker or QR ticket scanner.
On another occasion, a temporary results page on the National Lottery website displayed an incomplete list of raffle prizes following a Lotto Medal Event draw. Only 21 of the 88 prizes were displayed.
Among the other failings, which stretch back to 2016, were problems with direct debit instructions, security measures and Post Office controls, the Gambling Commission said.
The matters were “sufficiently serious” to warrant a financial penalty following the completion of its investigation that began in 2016.
Richard Watson, Gambling Commission executive director, said: “Camelot has taken a number of steps to rectify the issues and given us assurances that they now have the right processes in place to prevent reoccurrences.
“It is crucial that the National Lottery is run fairly, safely and with integrity and we’ll continue to hold Camelot to account.”
A Camelot spokesperson said: “We accept the outcome of the Gambling Commission’s investigation in respect of a number of incidents dating back to 2016.
“As part of the regulatory settlement, we have accepted the historical licence breaches identified, provided voluntary undertakings and will make a payment to National Lottery Good Causes in lieu of a financial penalty.
“While we have always sought to run The National Lottery to the highest possible standards, we accept that, at the time of these incidents, our standards in certain areas weren’t as rigorous as they should have been and for that we’re sorry.
“We’ve since proactively carried out an extensive programme of work to strengthen our controls, processes and governance arrangements to ensure they are all fit for purpose – and welcome the commission’s recognition of the work we’ve carried out to mitigate the risk of future issues.”