skin problem

Thank you for your report!
However, this issue has been temporarily closed as Awaiting Response.

We do not have enough information to find the cause of this issue.
Please force a crash by pressing F3 + C for 10 seconds while in-game and attach the crash report ([minecraft/crash-reports/crash-<DATE>-client.txt|http://hopper.minecraft.net/help/guides/finding-minecraft-data-folder]) here.

Once attached, the report will be reopened automatically.

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They are in 1.12.2

I don't think that F3+C works in 1.12.2

Couldn't confirm for MC 1.12.2. Do what Neko said. However, try to do deactivate all the texture packs and restart Minecraft. Often, all the texture bugs are caused by the texturepacks!

But i didn't use texture packs. And it often happen in other version like 1.10

Update your graphics driver to the latest available version and see if the issue persists.