<oembed><type>rich</type><version>1.0</version><author_name>npub1e46n428mcyfwznl7nlsf6d3s7rhlwm9x3cmkuqzt3emmdpadmkaqqjxmcu</author_name><author_url>https://nostr.ae/npub1e46n428mcyfwznl7nlsf6d3s7rhlwm9x3cmkuqzt3emmdpadmkaqqjxmcu</author_url><provider_name>njump</provider_name><provider_url>https://nostr.ae</provider_url><html>📅 Original date posted:2017-03-23&#xA;📝 Original message:I haven&#39;t investigated, but you may be seeing segwit-invalid blocks...0.13.0+ nodes will enforce segwit as it activated some time ago on testnet, 0.12.X nodes will not.&#xA;&#xA;On March 23, 2017 3:37:34 PM PDT, Juan Garavaglia via bitcoin-dev &lt;bitcoin-dev at lists.linuxfoundation.org&gt; wrote:&#xA;&gt;We notice some reorgs in Bitcoin testnet, while reorgs in testnet are&#xA;&gt;common and may be part of different tests and experiments, it seems the&#xA;&gt;forks are not created by a single user and multiple blocks were mined&#xA;&gt;by different users in each chain.  My first impression was that the&#xA;&gt;problem was related to network issues but some Bitcoin explorers were&#xA;&gt;following one chain while others follow the other one.  Nonetheless,&#xA;&gt;well established explorers like blocktrail.com or blockr.io were&#xA;&gt;following different chains at different heights which led to me to&#xA;&gt;believe that it was not a network issue. After some time, a reorg&#xA;&gt;occurs and it all comes to normal state as a single chain.&#xA;&gt;We started investigating more and we identified that the fork occurs&#xA;&gt;with nodes 0.12; in some situations, nodes 0.12 has longer/different&#xA;&gt;chains. The blocks in both chains are valid so something must be&#xA;&gt;occurring in the communication between nodes but not related with the&#xA;&gt;network itself.&#xA;&gt;Long story short, when nodes 0.13+ receive blocks from 0.13+ nodes all&#xA;&gt;is ok, and those blocks propagate to older nodes with no issues. But&#xA;&gt;when a block tries to be propagated from bitcoind 0.12.+ to newer ones&#xA;&gt;those blocks are NOT being propagated to the peers with newer versions&#xA;&gt;while these newer blocks are being propagated to peers with older&#xA;&gt;versions with no issues.&#xA;&gt;My conclusion is that we have a backward compatibility issue between&#xA;&gt;0.13.X+ and older versions.&#xA;&gt;The issue is simple to replicate, first, get latest version of&#xA;&gt;bitcoind, complete the IBD after is at current height, then force it to&#xA;&gt;use exclusively one or more peers of versions 0.12.X and older, and you&#xA;&gt;will notice that the latest version node will never receive a new&#xA;&gt;block.&#xA;&gt;Probably some alternative bitcoin implementations act as bridges&#xA;&gt;between these two versions and facilitate the chain reorgs.&#xA;&gt;I have not yet found any way where/how it can be used in a malicious&#xA;&gt;way or be exploited by a miner but in theory Bitcoin 0.13.X+ should&#xA;&gt;remain compatible with older ones, but a 0.13+ node may become isolated&#xA;&gt;by 0.12 peers, and there is not notice for the node owner.&#xA;-------------- next part --------------&#xA;An HTML attachment was scrubbed...&#xA;URL: &lt;http://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20170323/f7be920b/attachment.html&gt;</html></oembed>