As Ernesto noted, the leaderboard has successfully updated for all contests and should be back and updating as normal moving forward.
I'd like to give you some background as to the cause of the problem so you have some clarity as to what was happening behind the scenes. The root cause of the problem was that the benchmark data used by the leaderboard calculations began to fail. It failed unexpectedly because it was using pyfolio for the data and pyfolio was relying upon the Yahoo API for benchmark data. Using Yahoo data makes sense within the context of pyfolio since it is open source and the Yahoo data was freely available.
As many of you likely know, the (undocumented) API for this Yahoo data changed abruptly recently. This change caused a series of failures in quite a few of our open source libraries, pyfolio included. Once we sorted out the problems, we concluded that (of course) we needed to fix the leaderboard and that it should no longer rely upon Yahoo (or any other free API for that matter).
This part of our architecture had not previously accessed market data such as this so it was quite a bit more complex than a typical bug fix. In turn, once the development work was complete, this new code failed a variety of integration tests over the last few days, preventing it from coming out in a more timely fashion. We thought we were 'done' but our integration tests thought otherwise.
We're sorry that this bug lingered for so long. We know you invest a lot of time in the contest and your research on Quantopian and we will continually work to make the entire platform more robust, reliable and more powerful.
Thanks,
Josh
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