Version 593 was released on 2020-06-08. Since then, no new stalls have occurred. This page will be left in the documentation repository for historical reference.
Due to frequent stalls on the admission of new verifiers, we recommend temporarily closing the cycle to verifier admissions. While the stalls can be broken, these situations are incredibly stressful for everyone, and they cause credibility issues for the blockchain.
A short closure to new verifiers (2 to 3 days, most likely) would allow us to examine the problem in depth, replicate the issue on a testnet, and release a thoughtful, comprehensive solution without the distraction of rushing to release a fix before the next stall happens.
Also, a short closure will not have a huge impact on waiting verifiers. At the current rate of admission, the closure will likely eliminate fewer than 10 join windows.
To close the cycle, simply cast a manual new-verifier vote for an invalid identifier (such as 0000.0001). This can be done using NewVerifierVoteOverrideRequestScript. If enough verifiers cast an invalid vote, the new-verifier tally will be unable to exceed 50% for any valid verifier, and no new verifiers will be admitted.
We will also release an update shortly that will include a hard-coded vote override. This will be version 592. The override will be removed in version 593. Those who do not wish to close the cycle do not have to update to version 592. If a verifier skips over 592 to 593, they will never run the code that closes the cycle.