Disappointed Quality Street customers have taken to social media to complain that the selection is lacking a crucial ingredient.
"Where are the Chocolate Caramel Brownies?! My 8yr old son is devastated," wrote one.
Another customer complained they had been given extra Orange Cremes.
The company said that its manufacturing process was adversely affected during lockdown, resulting in a narrower range in some tins.
"In order to keep Quality Street production going during the Covid-19 lockdown period, we made some temporary changes to the way we operated, such as running fewer lines for a time," a spokesperson for Nestle said.
While there was no change to the overall weight being sold, the range had been affected, she said.
"As a result, some consumers may find that they do not have all 12 varieties of Quality Street sweets in their mix."
The full range of chocolates was being produced and incorporated into more recent boxes, she added.
"We apologise for any disappointment caused but hope consumers understand why it was necessary to make these changes during such unprecedented conditions," the spokeswoman said.
The limited edition Chocolate Caramel Brownies were removed from production for four weeks earlier this year.
When the lockdown was at its height, a number of factory workers were shielding or looking after children, which was why Nestle made the change.
The Quality Street chocolates that are normally in a tin include a mix of:
- The Purple One
- Coconut Éclair
- Strawberry Delight
- Orange Creme
- Orange Crunch
- Toffee Penny
- Toffee Finger
- Caramel Swirl
- Green Triangle
- Milk Choc Block
Other manufacturers have also been affected by the coronavirus crisis.
In June, Marmite-owner Unilever said production of its spread was hit by a shortage of brewer's yeast after pubs were closed in March during lockdown.
But in the main, food producers around the world have said they have too much stock as restaurants and others areas of hospitality close for business.