Contract verification on Blockscout for a local zkSync network

[Niet-Pham]

Hi everyone! I'm having some trouble verifying a smart contract on Blockscout that's connected to my local zkSync network.
This is my backend env

#blockscout-be
export CHAIN_ID=840201
export CHAIN_TYPE=zksync
export DATABASE_URL="postgres://postgres@127.0.0.1:5432/blockscout"
export SECRET_KEY_BASE="wSPS0J0jym6hmIMfK19hQhypQl0w4KHH7kljlkjlkjlkjljkljklZAbjNSBNXBE8F4rC4"
export ETHEREUM_JSONRPC_HTTP_URL="http://localhost:3050"
export ETHEREUM_JSONRPC_TRACE_URL="http://localhost:3050"
export ETHEREUM_JSONRPC_WS_URL="ws://localhost:3051"
export MIX_ENV=dev
export API_V2_ENABLED=true
export PORT=9001
export COIN="APT"
export COIN_NAME="APT"
export DISPLAY_TOKEN_ICONS=true
export ENABLE_ZKSYNC=true
export INDEXER_ZKSYNC_BATCHES_ENABLED=true
export INDEXER_ZKSYNC_BATCHES_CHUNK_SIZE=50
export INDEXER_ZKSYNC_NEW_BATCHES_MAX_RANGE=50
export INDEXER_ZKSYNC_NEW_BATCHES_RECHECK_INTERVAL=60
export INDEXER_ZKSYNC_L1_RPC="http://localhost:8545"
export INDEXER_ZKSYNC_BATCHES_STATUS_RECHECK_INTERVAL=50
export WEBAPP_URL="http://localhost:3000"
#blockscout-be microservices
export MICROSERVICE_SC_VERIFIER_ENABLED=true
export MICROSERVICE_SC_VERIFIER_URL="http://localhost:8082/"
export MICROSERVICE_VISUALIZE_SOL2UML_ENABLED=true
export MICROSERVICE_VISUALIZE_SOL2UML_URL="http://localhost:8081/"
export MICROSERVICE_SIG_PROVIDER_ENABLED=true
export MICROSERVICE_SIG_PROVIDER_URL="http://localhost:8083/"
export MICROSERVICE_SC_VERIFIER_ENABLED=true
export MICROSERVICE_SC_VERIFIER_URL="https://eth-bytecode-db.services.blockscout.com/"
export MICROSERVICE_SC_VERIFIER_TYPE=eth_bytecode_db

As far as I know, when navigating to the contract verification page, it calls the API http://localhost:3000/api/v2/smart-contracts/verification/config to fetch all available compiler versions.

However, when the CHAIN_TYPE=zksync environment variable is set, that API attempts to fetch compiler versions from the third-party endpoint https://eth-bytecode-db.services.blockscout.com/api/v2/zkysnc-verifier/solidity/versions, which returns null.

On the other hand, when CHAIN_TYPE=zksync is not set, it uses the endpoint https://eth-bytecode-db.services.blockscout.com/api/v2/verifier/solidity/versions, which correctly returns a list of Solidity compiler versions.

I’m not sure if I misconfigured something.
What is the correct setup to verify smart contracts on Blockscout (with a local zkSync network), and how can I make sure it fetches both solc and zksolc compiler versions correctly in the UI?

[ekawibisono]

hello @Niet-Pham , your env microservice has two, I will help you fix it and please try it

export MICROSERVICE_SC_VERIFIER_ENABLED=true
export MICROSERVICE_SC_VERIFIER_URL="https://eth-bytecode-db.services.blockscout.com/"
export MICROSERVICE_SC_VERIFIER_TYPE=eth_bytecode_db
export MICROSERVICE_VISUALIZE_SOL2UML_ENABLED=true
export MICROSERVICE_VISUALIZE_SOL2UML_URL="http://localhost:8081/"
export MICROSERVICE_SIG_PROVIDER_ENABLED=true
export MICROSERVICE_SIG_PROVIDER_URL="http://localhost:8083/"

try use this

[ekawibisono]

for more communication please join discord blockscout
https://discord.gg/blockscout/

[Niet-Pham]

Sorry for reopening the discussion, but I'm having some trouble building Blockscout using docker pull ghcr.io/blockscout/blockscout:latest.
When I try to verify a contract, I get the following log:

{"time":"2025-05-21T16:48:27.975Z","severity":"error","message":"Task #PID<0.223318.0> started from #PID<0.46079.0> terminating\n** (DBConnection.EncodeError) Postgrex expected a binary, got 3. Please make sure the value you are passing matches the definition in your table or in your query or convert the value accordingly.\n    (postgrex 0.20.0) lib/postgrex/type_module.ex:1084: Postgrex.DefaultTypes.encode_params/3\n    (postgrex 0.20.0) lib/postgrex/query.ex:75: DBConnection.Query.Postgrex.Query.encode/3\n    (db_connection 2.7.0) lib/db_connection.ex:1449: DBConnection.encode/5\n    (db_connection 2.7.0) lib/db_connection.ex:1549: DBConnection.run_prepare_execute/5\n    (db_connection 2.7.0) lib/db_connection.ex:772: DBConnection.parsed_prepare_execute/5\n    (db_connection 2.7.0) lib/db_connection.ex:764: DBConnection.prepare_execute/4\n    (postgrex 0.20.0) lib/postgrex.ex:296: Postgrex.query/4\n    (ecto_sql 3.12.1) lib/ecto/adapters/sql.ex:1150: Ecto.Adapters.SQL.struct/10\nFunction: #Function<3.82049945/0 in Que.Job.perform/1>\n    Args: []","metadata":{"error":{"initial_call":null,"reason":"** (DBConnection.EncodeError) Postgrex expected a binary, got 3. Please make sure the value you are passing matches the definition in your table or in your query or convert the value accordingly.\n    (postgrex 0.20.0) lib/postgrex/type_module.ex:1084: Postgrex.DefaultTypes.encode_params/3\n    (postgrex 0.20.0) lib/postgrex/query.ex:75: DBConnection.Query.Postgrex.Query.encode/3\n    (db_connection 2.7.0) lib/db_connection.ex:1449: DBConnection.encode/5\n    (db_connection 2.7.0) lib/db_connection.ex:1549: DBConnection.run_prepare_execute/5\n    (db_connection 2.7.0) lib/db_connection.ex:772: DBConnection.parsed_prepare_execute/5\n    (db_connection 2.7.0) lib/db_connection.ex:764: DBConnection.prepare_execute/4\n    (postgrex 0.20.0) lib/postgrex.ex:296: Postgrex.query/4\n    (ecto_sql 3.12.1) lib/ecto/adapters/sql.ex:1150: Ecto.Adapters.SQL.struct/10\n"}}}

However, when I verify using a manually deployed local build, I don’t encounter this issue.

Can anyone help me fix or resolve this problem?