I'm immediately failing to compile https://github.com/Blockstream/electrs on a clean branch of new-index as instructed in the README. The build is failing with the following error:

error: failed to run custom build command for `librocksdb-sys v6.20.3`


electrs/target/release/build/librocksdb-sys-3b3cba65ffc3c8e0/build-script-build` (exit status: 101)
  --- stderr
  thread 'main' panicked at '"enum_(unnamed_at_rocksdb/include/rocksdb/c_h_854_1)" is not a valid Ident'

My variation from the run command in the README.md is in trying to connect to Polar/Regtest data. The command is run based on feedback in related questions and I've verified that the directory exists for me.

cargo run --release --bin electrs -- -vvvv --daemon-dir ~/.polar/networks/1/volumes/bitcoind/backend1 --network=regtest

Any feedback on this particular issue would be greatly appreciated as well as any tips on running Esplora on regtest, that ideally expand on --lightmode.

OS: MacOS (Intel)
rustc: 1.72.1
cargo: 1.72.1
rustup: 1.26.0
  • Seems to be a version conflict between bindgen version < 0.62 via rocksdb, and clang version 15. I was unfortunately planning on using XCode 15 for the same project so this does create a material issue. Commented Dec 16, 2023 at 12:54
  • 2
    For what it's worth github.com/mempool/electrs is a maintained fork which serves the same purpose. Commented Dec 18, 2023 at 14:51
  • Its worth a lot! Thank you for responding @AntoinePoinsot Commented Dec 18, 2023 at 16:21

1 Answer 1


There were several steps I was able to take to resolve this at the expense of the librocksdb-oldcpu feature and optional dependency.

  1. Remove librocksdb-oldcpu dependency and feature
  2. Upgrade librocksdb to 0.21.0, this pulls bindgen up to >0.62.0.
  3. Update the Iterator implementation in src/new-index/db.rs to fix a breaking change on the response type of a function.

You can see the commit of my fork for this here.

I understand that this change optimizes for my machine and expediency so still looking for any insights into how others maybe using Electrum in Regtest today.

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