psbt: is upcoming v32 psbt v2 compatibility break intentional? #36518

1. 
   mjdietzx commented at 2:30 AM on October 14, 2026: contributor

   When psbt is created in gui it's now v2 (no option or indication in ui). Using core as wallet software with external signers may result in confusing errors if hw is not compatible with psbt v2. Also multisig users who have bitcoin core nodes on older versions than the node creating psbt will get an "unable to decode PSBT, unsupported version number: unspecified iostream_category error" when attempt to load psbt v2 on any node pre-v32.

   I was surprised to see a compatibility break like this so I want to double check that it is intentional

   Do users creating unsigned psbt through gui have use case for psbt v2? do we expect this to be more users than will be affected by compatibility break? Is it not be better to continue defaulting to psbt v0 in gui for compatibility, and users who need v2 new features would use cli anyways?

2. 
   achow101 commented at 2:37 AM on October 14, 2026: member

   Yes

3. fanquake added this to the milestone 32.0 on Oct 14, 2026
4. fanquake added the label PSBT on Oct 14, 2026
5. 
   fanquake commented at 8:05 AM on October 14, 2026: member

   This at least needs (more of) a release note (https://github.com/bitcoin-core/bitcoin-devwiki/wiki/32.0-Release-Notes-Draft only mentions v2 in the context of RPCs), and sounds like a workaround/similar in the GUI?

6. 
   mjdietzx commented at 2:30 PM on October 14, 2026: contributor

   GUI user gets nothing from psbt v2 today. GUI doesn't use the extensibility v2 provides and nothing in the GUI uses per-input locktimes. Meanwhile GUI users lose compatibility with pre-v32 nodes, possibly with external signers (I assume subset of hardware/software will fail to load/sign psbt v2), and disrupt any workflows where GUI-created PSBT is later passed to joinpsbts "joinpsbts only operates on version 0 PSBTs (-8)"

   Why not simply have GUI-created PSBT default to v0 and get rid of this entire concern?

Milestone
32.0