rpc dumptxoutset breaks with default optional value. #34255

1. 
   jaoleal commented at 7:02 pm on January 11, 2026: none

   Is there an existing issue for this?

   • I have searched the existing issues

   Current behaviour

   I was testing dumptxoutset and by omitting the type field the command just broke even if the field itself claims to be optional.

   In the documentation it says that the default value for type is " " but appears the command is expecting either rollback or latest.

   Expected behaviour

   Since the documentation is already stating the problem itself, this may be a desired behavior ? But why make the field optional if thats not exactly the case ? Why not making the default value for type to be latest ?

   Steps to reproduce

   bitcoin-cli dumtxoutset filename.dat

   Relevant log output

   [nix-shell:~]$ sudo bitcoin-cli -rpcclienttimeout=0 dumptxoutset pau.dat [sudo] password for jaoleal: error code: -8 error message: Invalid snapshot type "" specified. Please specify “rollback” or “latest”

   How did you obtain Bitcoin Core

   Package manager

   What version of Bitcoin Core are you using?

   v30.0

   Operating system and version

   NixOs 25.11

   Machine specifications

   Enough

2. 
   maflcko commented at 7:41 am on January 12, 2026: member

   It is only optional to specify type="rollback", when rollback=... is set. Otherwise, the error is correct:

   Invalid snapshot type "" specified. Please specify “rollback” or “latest”

3. maflcko closed this on Jan 12, 2026

   ---

4. maflcko added the label Docs on Jan 12, 2026
5. maflcko added the label RPC/REST/ZMQ on Jan 12, 2026
6. maflcko added the label Questions and Help on Jan 12, 2026
7. 
   maflcko commented at 7:42 am on January 12, 2026: member

   Closing for now, because I think this is clear, but pull requests with suggestions or improvements are welcome, if there are any.

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jaoleal maflcko

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