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Negative UNL is an experimental feature currently in testing on Devnet based on one of David Schwartz's wild ideas for how to improve the XRP Ledger. The idea behind this feature is it adds an on-ledger list of trusted validators who are believed to be offline, and adjusts the validation requirements accordingly, within safety limits, so that the ledger can continue to make progress even if several trusted validators are temporarily down. Negative UNL is present in rippled v1.6.0 as a "pre-amendment" feature, meaning you can force it on for a particular server for testing purposes but you can't vote for it in the amendment process. Detailed documentation on Negative UNL is now available on xrpl.org. Note: Negative UNL affects the local "validation" step after a consensus has been declared, but not the transaction-set-choosing part of "consensus". It's a fine distinction but important to understanding Negative UNL well. Since any change to consensus is fairly consequential, we at Ripple are being very cautious about how we roll out this feature. Right now, we believe that there are some specific situations where Negative UNL can decrease the overall fork-safety of the network, but those situations are rare enough that they are extremely unlikely to arise in practice. Meanwhile, the situations where Negative UNL improves the overall liveness of the network are plausible, so it is probably worth the tradeoff. That being the case, we are testing Negative UNL now and will probably not propose it as an amendment until rippled v2.0. We are also encouraging academic research and analysis of the implementation now so that we can be certain that the impacts are as we suspect they are. If it turns out that Negative UNL does not work as well as we though it would, we still have the option to tweak this approach or throw it out entirely. If you're interested in consensus algorithms and the overall reliability of the XRP Ledger network, please take a look at the documentation and don't hesitate to ask questions.

XRP Ledger core server, rippled, v1.5.0 has been released! You can read the full v1.5.0 Release Announcement on the XRPL Blog. Also, we've published a whole bunch of changes to the documentation on xrpl.org, including: Known Amendments has the new protocol amendments listed and statuses updated: https://xrpl.org/known-amendments.html New fields in the response to the submit method: https://xrpl.org/submit.html#response-format server_info method updated with more recent examples and updated time fields: https://xrpl.org/server_info.html New manifest method: https://xrpl.org/manifest.html New validator_info method: https://xrpl.org/validator_info.html New fields in tx method providing for more robust Not Found errors: https://xrpl.org/tx.html#not-found-response Updated account_channels method to reflect bug fixes: https://xrpl.org/account_channels.html Instructions on how to enable the new gRPC API on your rippled server: https://xrpl.org/configure-grpc.html New warnings in API responses if your server is, or is about to be, amendment blocked: https://xrpl.org/response-formatting.html#api-warnings Request Formatting updated with better formatting and new API Versioning information: https://xrpl.org/request-formatting.html Other very minor cleanup and corrections Let me know if you have any questions or comments, and enjoy the new version!

Hi all, I've been trying to do some tests with checks (https://xrpl.org/checks.html) for a project of mine. I'm using the test net (wss://s.altnet.rippletest.net:51233). I can successfully do checkCreate transactions but cannot seem to do a checkCash (tecNO_ENTRY: No matching entry found). I'm using ripple-lib in order to generate those checks. The currency used is XRP, not an issued currency. The test is for 1 XRP or 1000000 drops. Here's the checkCreate transaction: https://testnet.xrpl.org/transactions/F0A3342809F466A216D7930F3001AAAC3CC41877BFEA29A3CC88B4781CC4AC41 Here's the failed checkCash transaction: https://testnet.xrpl.org/transactions/25C901046A4E97B262448EBE339EDC00BBEFDB8366F3ED2E7D499089E8CE6671 The checkID used to do the checkCreate and checkCash is: ABCDEFABABCDEFABABCDEFABABCDEFABABCDEFABABCDEFABABCDEFABABCDEFAF I just can't figure out what I'm doing wrong. I've read the documentation on xrpl.org, tried with 'drops' and 'XRP' as currencies (both ways are used in the doc) but I always get a tecNO_ENTRY. Maybe the Check amendment is not active on the test net node I'm using? How can I know that? Thanks a bunch for your help.