There can't be seen as simply one failure, but many, some of which occur after the "20 year rule" comes into play. However, I think the biggest failure isn't in the 1993 Agreement, but the negotiations that came after. I'm bending the 20 year rule slightly because I think the "Post-Oslo Era" of negotiations really goes up to 2000, with the failure of the Camp David Summit. After that, for a variety of reasons, the character of negotiations change. I want to say as recently as 2008 there seemed to be the major possibility of peace in the short term (though how real this possibility was is, like everything, contentious). We have gone from an era where we expected that maybe this year or next would bring a final status agreement to an era where we're not even sure if they'll be negotiations to have further negotiations this year or next.

One big post Oslo-change was the Rabin assassination, which removed from the equation a popular Israeli leader who made major progress and was one of the few times I saw my father cry (I remember him grabbing my arm, I was about eleven, and trying to instill in me the fact that "Yitzhak Rabin was a good man"). However, it should be pointed out that his successor, Shimon Peres, was PM until being defeated by Netanyahu in 1997. He was Rabin's main negotiator, as well as a co-recipient along with Rabin and Arafat of the Nobel Peace Prize. He made little leeway, however, before the next elections.

While Rabin and Peres were in the "Peace Camp", Netanyahu was not. However, he renogiated the status of Hebron to give the PA more much more power, creating H1 and H2. He did also participate in the Wye River Memorandum, and continued negotiations generally. However, he also stopped the implementation of the Wye River Memorandum, thus halting the transfer of more land to increased Palestinian Authority that was envisioned as part of the Oslo framework. Even before he was prime minister, though, Netanyahu criticized what he called Arafat and the PA's "revolving door policy" on terrorism. I believe he also refused to discuss the final status of Jerusalem.

All was no lost, however, with Netanyahu's halting the transfer of land from Areas C and B to Areas B and A. The Camp David Summit between Arafat and Netanyahu's successor Barak were promising, and both sides were very close to outlying exactly what the final status would look like. The Israelis under Barak even agree to the so-called "Clinton parameters". Clinton firmly blamed the failure of the talks on Arafat, who never said no but also could never bring himself to say yes before the negotiations and shortly thereafter Clinton's term of office ended. You can read the relevant section of Clinton's biography here, it says a lot. Clinton called Arafat's rejection of the Clinton Parameters a "a colossal mistake". He goes into detail about the Israeli agreement and Arafat's wavering and ends with:

As a backstop, the Israelis tried to produce a letter with as much agreement on the parameter as possible, on the assumption that Barak would lose the election and at least both sides would be bound to a course that could lead to an agreement. Arafat wouldn’t even do that, because he didn’t want to be seen conceding anything. The parties continued their talks in Taba, Egypt. They got close, but did not succeed. Arafat never said no; he just couldn’t bring himself to say yes. Pride goeth before the fall.

Right before I left office, Arafat, in one of our last conversations, thanked me for all my efforts and told me what a great man I was. “Mr. Chairman,” I replied, “I am not a great man. I am a failure, and you have made me one.” I warned Arafat that he was single-handedly electing Sharon and that he would reap the whirlwind.

Shortly, after the failure of Camp David, things changed remarkably. Hardliner Sharon beat Barak; the Second Intifada broke out with unprecedented levels of violence against Israeli civilians; Israel responded to the Second Intifada more successfully with security measures than negotiations; Sharon tried unilateral withdrawal from Gaza which failed to achieve his goals; Hamas and Fatah split, also splitting the governments of Gaza and West Bank, making negotiations harder; a strengthened, autonomous Hamas alone made negotiations much more difficult. You see a shift from the Camp David Summit like negotiations of an actual final settlement to broader negotiations on how to negotiate a final settlement with the Road Map for Peace just two years later, and continued with Annapolis in 2007. You can also see Sharon's strategy, with things like the unilateral withdrawal, was very different from the post-Oslo strategy of negotiations. From the failure of Camp David on, the idea that "we have no partner for peace" has become increasingly entrenched in Israel, and not just on the right. The meme is so common it's mocked on the Israeli equivalent of Saturday Night Live. Later, Palestinians too have adopted a different negotiating strategy than the Post-Oslo one, trying to make their case to international organizations like the UN to put external pressure on the Israeli negotiators to speed up a time table, in part because the idea that "the Israelis will never give up the settlements" has become more entrenched. Oslo was not just an agreement, but as window, and one that closed.

In the end, I think Oslo's failure was not in the text itself, but in the failure of subsequent talks before the window of post-Oslo talks "closed" after Camp David, with both Sharon and the Second Intifada looming large in the immediate aftermath. It's hard for me to imagine a Post-Olso agreement looking very different from the Clinton Parameters of 2000, and it's now depressingly easy to imagine never returning to that point in my lifetime.

Like the other user, who I have points of disagreement with throughout, I don't think you can adequately cover that unless you can go to at least 2000. However, given this goes a few years into the 20 year rule, and requires subsequent discussion, I'm going to just reserve my objections to the other user's comments and claims and leave it at that. You are better off asking this in another subreddit like /r/ask_politics, in my view.