[MCL-12569] Unable to save skin / unable to duplicate skin

Bug Duplication

This issue is being tracked as ~~MCL-14579~~. See that bug for possible workaround and if you want to add additional information.

Every time I try to create a skin profile for the launcher 2.1.9616, the skins can be saved or duplicated. There would be an error message on the top right corner saying "Unable to duplicate skin" or "Unable to save skin".

I've tried to reinstall the Minecraft launcher but when I did nothing changed.

The file of "launcher.skins.json" in my .minecraft folder only says "null".

I can apply the default skins with no problems but saving my custom skins causes a problem.