Betfair recently introduced changes and new rules to their API to prevent consistent attempts to take advantage of bet rounding.
For example – a 13p @ 1.06 back bet is ‘unfair’ as it ‘ought’ to win 0.78p, but actually - due to the old rounding - wins 1p, which is a 28% uplift in profit
Bet Angel has been updated since these changes to still allow users to green up when using small stakes below the £2 Betfair minimum, but it does mean it there maybe times when your P/L now ends up uneven by a few pence due to this new Betfair rule - if that happens you will see an error written to your Bet Angel log which looks like;
" While Greening Up Unable to Place Lay Bet Due to Befair's Rules Regarding Payout/Liability Rounding"
See the image below for a explaination and example from Betfair posted on their developers forum.