Bitcoin Forum

A question if a miner submit a block and marked as orphaned can re submit it ? what are the chances a blockexplorer to shows a block as orphaned when the block is valid ?

No, he can't. There isn't any "known parent" (https://en.bitcoin.it/wiki/Orphan_Block) to that block.


Error from the blockchain explorer, or the blockchain explorer followed a fork.

i know that that he cant,but i see something which made a little to be surprised,i see a block in blockchain.info as orphan and then as vaild

That just means blockchain.info was originally looking at the wrong fork that then ended up losing the orphan race to see which block eventually became labelled as valid.

Note: the miner who their block marked as orphan is the same miner when their block marked as valid

Thank guys

There are two possibilities...


1.  The very likely possibility.  Blockchain.info has a bug and displayed the block as orphaned when they shouldn't have.  Later they fixed the problem and showed the block as not orphaned.


2.  The much less likely possibility.  The block became orphaned, and then became not orphaned.  This doesn't require the miner to re-submit the block.  It just requires that the orphaned fork grow long enough to be the longest chain.

Theoretical example:

• The entire network agrees that block 449859 mined by F2Pool is the most recent block in the consensus chain.
• You and I both mine a block (449860) on top of that at almost the exact same time.  We both broadcast our block to the network.  Due to the time it takes the blocks to propagate across all the nodes, approximately half the network thinks your block is valid (and doesn't even see mine), and approximately half the network thinks my block is valid (and dosen't even see yours).
• Someone that received my block mines a block on top of it (449861 on top of my 449860). They broadcast their block to the network.  Now the chain with my block is longer than the chain with your block (it has this extra new block), so your block becomes orphaned.
• Nodes that had previously received your block start to abandon it and switch to my chain.
• Before all the nodes and miners that were previously working on your block hear about my block, someone that had received your block mines a block on top of it (449861 on top of your 449860). They broadcast their block to the network, and some of the nodes hear about the second block on top of yours before they hear about the second block on top of mine.  These nodes ignore my chain since it is the same length as the one they already have with your block. So now the network is still split, but most of the network (including blockchain.info) has sees my chain as valid and your block as orphaned.
• One of the few miners that didn't switch to my chain solve a block (449862 on top of 449861 on top of your 449860) and broadcasts it.
• Your chain is now longer than my chain.  Nodes that had previously received my block (and the one block on top of it) start to abandon both of those blocks and switch to your chain that has 2 blocks on top of your block.
• My block and the one on top of it become orphans, and your block (and the two blocks on top of it) become the consensus chain.
• blockchain.info's nodes see this new consensus chain and their database is updated to switch your block from orphaned back to valid
• The entire network eventually sees this new chain with your valid block and my orphaned block.  All the miners are now working to solve block 449863 which will be on your chain.

Just to add something, I noticed Blockchain.info is not updating or reflecting the situation as quickly as other block explorers for some reason. I have 3 transactions unconfirmed for more than 18 hours at the moment, and when I use Blockchain.info, it does not even show that the transactions are unconfirmed.

When I used https://blockexplorer.com it showed the status immediately. So this might just be a bug in Blockchain.info software. < A delay between what is shown, and what the real situation is > ^hmmmmm^