An accidental knot

Hi,

One may not untie a knot on Shabbat, but one may un-do a slipknot.

Where someone attempted to tie on a hat or hood on Shabbat with a slipknot, to permit untying, but then they made it into a knot by accident, they may untie the knot. This is the law because leaving the hat/hood on all day would be upsetting, and because the intent from the beginning was to untie it.

(Rivivot Ephraim 1:222:17)

חג אורים שמח,
Mordechai