<p>Why SegWit-incapable miners won't include SegWit tx's in their blocks but will accept as valid someone else's block with SegWit tx's in it?</p>

CC BY-SA 4.0
2019-01-21T16:19:09.647Z
https://bitcoin.stackexchange.com/questions/42634/can-unupgraded-nodes-that-accept-zero-confirmation-be-fooled-after-segwit/42642
G. Maxwell
CC BY-SA 4.0
2019-01-21T16:29:32.330Z
@G.Maxwell "Among old nodes, the transaction is not propagated because it is non-standard", but how these tx's are accepted as valid by old nodes when inside a mined block?
João Grilo Bitcoinheiro
CC BY-SA 4.0
2019-01-21T16:34:36.743Z
If a pre-segwit miner would include a segwit tx in a block (which they won't accidentally do, due to nonstandardness), that block will be invalid to segwit miners. The latter would just ignore that block and build a chain that does not include it.
Pieter Wuille
CC BY-SA 4.0
2019-01-21T16:39:36.817Z
@PieterWuille, this I understand, but what about the other way around? Do pre-segwit miners receive blocks by segwit miners with segwit tx's in them and accept them as valid? Being "nonstandard" and "valid" are different things?
João Grilo Bitcoinheiro
CC BY-SA 4.0
2019-01-21T16:42:48.447Z
Nonstandard means "won't relay or include in a block" (which is a local policy). Invalid means "would be invalid in a block" (which is a network wide rule). Segwit has been constructed such that a block with witness transactions will be valid to pre-segwit nodes.
Pieter Wuille
CC BY-SA 4.0
2019-01-21T16:47:16.347Z
@PieterWuille , perfectly clear now. Thank you for the attention and patience
João Grilo Bitcoinheiro
<segregated-witness>
SegWit-incapable miners won't include SegWit tx's but accept them as valid?
João Grilo Bitcoinheiro
# SegWit-incapable miners won't include SegWit tx's but accept them as valid?

(Asked by: username_0 on 2019-01-21)

Why SegWit-incapable miners won't include SegWit tx's in their blocks but will accept as valid someone else's block with SegWit tx's in it?

**Tags:** segregated-witness

> **Comments:**
> **username_1**: https://bitcoin.stackexchange.com/questions/42634/can-unupgraded-nodes-that-accept-zero-confirmation-be-fooled-after-segwit/42642  
> **username_0**: @G.username_1 "Among old nodes, the transaction is not propagated because it is non-standard", but how these tx's are accepted as valid by old nodes when inside a mined block?  
> **username_2**: If a pre-segwit miner would include a segwit tx in a block (which they won't accidentally do, due to nonstandardness), that block will be invalid to segwit miners. The latter would just ignore that block and build a chain that does not include it.  
> **username_0**: @username_2, this I understand, but what about the other way around? Do pre-segwit miners receive blocks by segwit miners with segwit tx's in them and accept them as valid? Being "nonstandard" and "valid" are different things?  
> **username_2**: Nonstandard means "won't relay or include in a block" (which is a local policy). Invalid means "would be invalid in a block" (which is a network wide rule). Segwit has been constructed such that a block with witness transactions will be valid to pre-segwit nodes.  
> **username_0**: @username_2 , perfectly clear now. Thank you for the attention and patience  

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## 0 answers

