Vinted users have been reacting angrily following a change that caused listings displaying inaccurate size information.
This online marketplace has revised its size classifications for women's and children's garments but did not contact every member regarding the update.
Numerous buyers and vendors have taken to social media saying Vinted listings now show a modified sizing category than originally posted because of the remapping.
Vinted explained the revised method more closely matches other platforms.
They have suggested members to examine their items and manually change the size when needed, causing user dissatisfaction.
Before the change, the sizing featured one number and one letter, like S/8 or M/10.
The updated approach includes an alphabetical indicator and numerical range such as S/UK 8-10.
In some cases, the size labels have been reassigned - for example a size L was previously a 12 but now shows as UK 16-18.
Frankie Bridger, who produces content about larger sizing, stated the update "complicates both purchasing and selling".
"Not many brands say XL is a 20-22," the way the service now categorizes.
Another user, based in Glasgow, stated items she posted on Vinted with size 14 labels were showing in the marketplace as measurements 20-22.
"Should someone sized 20-22 purchase these they will likely be quite upset," she stated.
A different user, located in England, stated she felt frustrated because the modification necessitated personal updates the sizing for "all her products".
"This situation is especially annoying, since I have chronic health issues and Vinted sales have been crucial following partial earnings loss," she stated.
The platform boasts over 100 million members, comprising 18 million UK members.
It has proved a popular alternative to second-hand platforms like eBay and Depop.
This is not the initial instance that an unexpected update to the app has proved unpopular: earlier, Vinted reversed a change regarding delivery choices due to shopper criticism.