Rack seems to have [a similar problem](https://github.com/js-cookie/js-cookie/issues/70#issuecomment-132503017).

It seems that there is a situation where Tomcat does not [read the parens correctly](https://github.com/js-cookie/js-cookie/issues/92#issue-107743407). To fix this you need to write a custom write converter:

var Cookies = Cookies.withConverter({

write: function (value) {

// Encode all characters according to the "encodeURIComponent" spec

return encodeURIComponent(value)

// Revert the characters that are unnecessarly encoded but are

// allowed in a cookie value

.replace(/%(23|24|26|2B|3A|3C|3E|3D|2F|3F|40|5B|5D|5E|60|7B|7D|7C)/g, decodeURIComponent)

// Encode the parens that are interpreted incorrectly by Tomcat

.replace(/[\(\)]/g, escape);

}

});