[BUG] Unable to open file: ./target/vk

[alxkzmn]

What are you trying to do?

Normal UltraHonk proving fails if the verification key file is not present, even though the vk should not be required for proving.
Notice that bb prove CLI command correctly does not require the verification key.
Example output:

[sha256] Circuit witness successfully solved
[sha256] Witness saved to target/sha256_128.gz
[sha256] Circuit output: [14, 100, 181, 4, 66, 209, 71, 12, 173, 4, 142, 11, 212, 231, 231, 51, 118, 254, 196, 64, 201, 244, 198, 152, 120, 249, 61, 206, 80, 253, 212, 32]
Scheme is: ultra_honk, num threads: 3 (mem: 6.56 MiB)
Unable to open file: ./target/vk

Code Reference

https://github.com/privacy-ethereum/csp-benchmarks/blob/d19659633f14bf6a7dd9774b7d4c06180720b19f/barretenberg/sha256_prove.sh
CI run log:
https://github.com/privacy-ethereum/csp-benchmarks/tree/d19659633f14bf6a7dd9774b7d4c06180720b19f/barretenberg/circuits

Aztec Version

bb 1.2.0, Noir beta.13

OS

OSX

Additional Context

Works fine with Noir beta.13 and bb 0.87.0

[TomAFrench]

This was changed in #14822, if you want to compute the VK while proving then you need to pass --write_vk.

[alxkzmn]

I see, would be nice if you update the docs as well!

[TomAFrench]

cc @AztecProtocol/devrel

[Savio-Sou]

Docs updated #12839 🙌