The tradition that is being changed, the doctrine that is being rejected in at least some cases, is the prohibition for the divorced and civilly remarried to partake in Communion.
Here is what Pope John Paul II said in his apostolic exhortation, Familiaris Consortio, paragraph 84:
Contrast that to what Pope Francis says apostolic exhortation Amoris Laetitia, paragraph 298 and its footnote 329:
Tradition or practice, according to Pope John Paul II, does not allow for ANY reception of Communion based on Sacred Scripture’s clear teaching on what constitutes adultery and grave scandal to the faithful. New practice according to Pope Francis is to not pigeonhole divorced into overly rigid classifications (such as how Pope John Paul II classified them?). Pope Francis says the Church acknowledges situations when the divorced remarried cannot separate and goes on to justify keeping the second union intact by referencing Gaudium Spes allowing married couples to periodically live as brother and sister when woman is fertile.

Paragraph 84 of FC stating that “complete continence” is one of necessary requirements for D&R to receive Communion is completely ignored. Instead, D&R are exhorted to practice “periodic continence” like those who practice NFP for grave reasons.
pnewton, is this not changing the practice of an established tradition based on clearly defined doctrine? Which Pope is correct in exhorting the faithful to live in a particular manner that accurately reflects the perfection we are called to attain before we can enter heaven?