If two miners solve a block at the same time, they are both added to the block.
A stale block is a block that has been dropped from the blockchain.
A stale block does not have at least 6 confirmations.
It is important to wait (and not get too excited) until more than one confirmation has occurred because,
the transaction my not have more confirmations. It would then become a stale block…transaction is returned to the mempool waiting room.
Its true that a stale block probably won’t have more than 6 confirmations, but its not really the rule. A stale block was the block that got dropped because a block on a competing chain with higher PoW was found. 
Blocks propagate ‘almost’ always within time to all other nodes before the next block gets mined in approximately in 10 minutes.
The 6 blocks waiting time is just for being sure that your transaction is on the blockchain forever.
Because the more blocks get mined since your transaction is in a block the more difficult it gets for a miner to mine a larger chain within the time a new block gets mined again.
*Every new mined block on top of the block where your transaction is in, means a new confirmation)
So if your transaction has 6 confirmations, it means that 5 new blocks are mined after the block where your transaction is in.
If 2 miners mine a new block at the same blockheight around the same time, you basically get 2 different blockchains propagating to the network. Each blockchain will have a different last block on that blockheight. These are 2 valid blockchains according to the bitcoin consensus rules.
But eventually, 1 of the 2 different versions of truth will get dropped. Because in Bitcoin, we have a rule that nodes with the longest blockchain (with more proof of work) will be the accepted blockchain. So once another miner successfully mines a new block on 1 of the 2 different blockchains, It will become a longer chain with 1 extra block than the other competing blockchain, with a different block. That block will become a stale block and all transactions that aren’t already included in that other accepted chain, will go back to the mempool.
[quote=“ivan, post:1, topic:8434”]
What happens in the bitcoin network when two miners solve a block at the same time?
Both blocks get appended but 2 chains form and eventually the shortest one becomes stale and all transactions return to the mempool as UTXOs
What is a stale block?
A block that becomes shorter after the chain forks
How do stale blocks occur?
When 2 miners solve a block at the same time and the chain forks
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
To guarantee that your transaction has been confirmed (i.e. it was not part of a stale block of transactions that needs to be mined again
What happens in the bitcoin network when two miners solve a block at the same time?
Answer: They are both considered True via the nodes but the block that is the longest, meaning if another miner appends to one of the blocks, and makes it longer, then that will be the one that gets confirmed.
What is a stale block?
Answer: It’s the same as an orphaned block that was not picked up or left because another block was appended instead due to it being a longer POW/Chain.
How do stale blocks occur?
Answer: It occurs when it is dropped for another block that got appended even though the stale block was true as was the other block but was longer in the chain. It occurs when two miners solve the same crypto puzzle at the same time but one is left orphaned because the other was added and confirmed in lieu of this one.
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction? Because other although the other nodes proved it to be true, the tx of this block would end up being removed because the other block that was accepted to the blockchain invalidated this block so it would no longer be a valid block after the other confirmations and acceptance
Both blocks get appended to the blockchain, however some nodes get one miner’s blockchain propagated and other nodes get another.
Stale block is a dropped block that gets invalidated because other miners chose another block to append to.
With two valid blockchains the one that is the longest is the truth. New blocks from the shortest blockchain get invalidated and its TXs return to the mempool and the block becomes stale.
To make sure that the transaction doesn’t live inside a stale block.
What happens in the bitcoin network when two miners solve a block at the same time?
the chain creates two extensions of itself temporarilty
What is a stale block?
the last block produced that had shortest/less PoW compared to the other
How do stale blocks occur?
They occur by not getting included in the chain
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
To make sure the block is not part of the chain that is going to be dropped at the temporary fork.
Both of them propagate their blocks to the network and as time goes by the network chooses the longest chain
The blocks that dropped back to the mempool
It happens if two miners solve the puzzle at the same time. Both blocks are added to the blockchain but only one is used.
Waiting for multiple confirmations allows sufficient time for the network to solidify the blockchain
What happens in the bitcoin network when two miners solve a block at the same time?
Both blocks will be added to the blockchain which effectively now creates 2 chains.
What is a stale block?
One of the chains will have new blocks added and becomes the longest chain and the confirmed blockchain. The block on the shorter chain is then called a stale or orphaned block. The stale block has it’s transactions returned to the mempool for re-mining.
How do stale blocks occur?
As discussed in answer 2 above.
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
It is best to wait 6 confirmations to ensure your transactions are confirmed and are not in a stale block and returned to the mempool.
Both blocks are true. The first block to have a block propagated/mined after it becomes valid. The other one becomes orphaned.
An orphaned block on the shorter blockchain occurs if two true blocks are found simultaneously.
Stale blocks occur when two blocks are valid yet only one becomes confirmed as the blockchain continues off it. As it gets solved first.
Important to wait for 6 confirmations to ensure your block isn’t dropped from the chain. In case your block becomes orphaned.
Both miners broadcast their respective versions of the next block as they both have nonces that make hashing algorithm produce am output that is lower than the difficulty level. All nodes will attempt to work off the longest chain delivered to them first.
A stale block is a block that was accepted by a part of the network but was surpassed by a different chain created at the same time.
A stale block occurs when multiple blocks are accepted at the same time, the network splits, a new block is created on one of the sides and the other block is discarded returning any transaction that weren’t in either the new block or the forked block back to the mempool.
The more blocks that have passed the less likely that a block will become stale. After six or more confirmations it is highly unlikely that a block will become stale meaning the transactions will have taken place and been accepted by the network as truth and won’t be returned to the mempool as it has already been removed from every mempool on the network.
1. What happens in the bitcoin network when two miners solve a block at the same time?
Each block will start propagating through the network. At some point one will be part of the shorter blockchain and will become a stale block.
2. What is a stale block?
Stale block is a block that was once a part of the valid blockchain that later on turned out to be shorter than other valid blockchain in network.
3. How do stale blocks occur?
If there are more than one valid blockchains propagated in network the longest one is chosen, causing the blocks from shorter ones to become stale.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
It’s good to wait for at least 6 confirmations to make sure that the block with the transaction is included in blockchain that was chosen by network and not returned to the mempool.
The miners will have competing versions of the blockchain.
A stale block, is a block which has been apart of the blockchain but has been dropped.
A stale block occurs when there are competing versions of the blockchain and when a chain gets chosen (longest proven pow chain wins), all blocks from competing chains that were not apart of the other chain are dropped and the transactions go back to the mempool.
It is important to wait, due to the likelihood of stale blocks happening from a competing block chain. The more confirmations the higher the likelihood of the blocks surviving.
What happens in the bitcoin network when two miners solve a block at the same time?
Both blocks will propagate the network until one chain of blocks is longer than the other. The shorter blocks will be dropped or orphaned. The dropped transactions are returned to the mempool.
What is a stale block?
A stale block is block that has been dropped from a shorter blockchain, due to a longer blockchain being used by the network.
How do stale blocks occur?
Stale blocks occur when blocks are propagated at the same time by different miners, and one of the blockchains becomes longer and accepted by the network. The other unused blockchain is then orphaned or considered “stale,” and then it’s transactions returned to the mempool.
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
Six confirmations is standard practice in crypto. It’s important to wait for six confirmations, or six blocks after your current block to ensure proper consensus, and that your transactions are not dropped from the blockchain.