an error occurred after updating

An error occurred after updating.

I can create new perm in the old save mod, but I can not change the old elements. In mcreator everything changes, but when you save the mod and test it in the game, the items do not change.

example:

in 2020.4 there was a sword with an icon of 1 and damage of 4 units

in 2020.5 the sword remained and after editing it began to have an icon of 2 and damage of 6 units, but when entering minectaft the sword has an icon 1 and damage 4

P.S.

1.the newest version of the mod has been removed correctly

2.English is not my native language