Vinted users have been reacting angrily after an update resulted in products showing incorrect sizing.
The second-hand shopping app has revised its size classifications for women's and children's clothes but did not contact all users about the change.
Many shoppers and sellers are expressing on platforms claiming that product pages now present a modified sizing category compared to what was initially listed due to the recalibration.
Vinted explained the new system was more in line with comparable marketplaces.
The platform has recommended to examine their items and adjust the sizing manually when needed, which has left users frustrated.
Previously, the sizing featured one number and one letter, such as S/8 or M/10.
The updated approach includes a letter with a size spectrum for example S/UK 8-10.
In some cases, the measurements have been reclassified - for example a size L was formerly size 12 but now shows as UK 16-18.
Frankie Bridger, who produces content about larger sizing, explained the modification "makes transactions more difficult".
"Rarely do manufacturers list XL as sizes 20-22," the way the service now categorizes.
Stephanie Gallen, from Glasgow, explained products she uploaded with size 14 tags were displaying on the service as measurements 20-22.
"If buyers measuring 20-22 acquire them they're going to be very disappointed," she stated.
A different user, from Derby, explained she became annoyed by the change as she had to manually change the sizing for "all her products".
"This situation is especially annoying, as I'm chronically ill and selling on Vinted has been paramount after experiencing income reduction," she stated.
The platform boasts over 100 million users, comprising 18 million UK members.
It has become a favored option compared to resale services such as eBay and Depop.
This isn't the first time when a surprising modification to the app has proved unpopular: last year, the service retracted a modification concerning shipment methods after backlash from users.