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Last update: April 28, 2021


If Hyperledger Besu is not working as expected, here are some things to check or try.

Supplied genesis block does not match stored chain data

If a Supplied genesis block does not match stored chain data error occurs, use the genesis file matching the genesis block of the data directory, or use the --data-path option to specify a different data directory.

Host not authorized

If a Host not authorized error occurs when attempting to access the JSON-RPC API, ensure --host-allowlist includes the host you are sending the RPC from, or *.

Peers fail to connect

If nodes are not communicating, ensure the required ports are open.

If your nodes are running in AWS, check you have appropriate SecurityGroups to allow access to the required ports.

Check that the enode URLs specified for bootnodes or static nodes match the enode URLs displayed when starting the remote nodes.


Check block creation. On mining nodes, log messages indicate block creation.

2019-05-08 20:28:27.026+10:00 | pool-10-thread-1 | INFO  | IbftRound | Importing block to chain. round=ConsensusRoundIdentifier{Sequence=660, Round=0}, hash=0x759afaba4e923d89175d850ceca4b8ef81f7d9c727b0b0b8e714b624a4b8e8cc
2019-05-08 20:28:29.020+10:00 | pool-10-thread-1 | INFO  | IbftRound | Importing block to chain. round=ConsensusRoundIdentifier{Sequence=661, Round=0}, hash=0x5443e504256765f06b3cebfbee82276a034ebcc8d685b7c3d1a6010fd4acfa14

On non-mining nodes, log messages indicate importing blocks.

2019-05-08 20:28:29.026+10:00 | EthScheduler-Workers-1 | INFO  | BlockPropagationManager | Imported #661 / 0 tx / 0 om / 0 (0.0%) gas / (0x5443e504256765f06b3cebfbee82276a034ebcc8d685b7c3d1a6010fd4acfa14) in 0.000s.
2019-05-08 20:28:31.031+10:00 | EthScheduler-Workers-0 | INFO  | BlockPropagationManager | Imported #662 / 0 tx / 0 om / 0 (0.0%) gas / (0x0ead4e20123d3f1433d8dec894fcce386da4049819b24b309963ce7a8a0fcf03) in 0.000s.

To confirm the block number is increasing, use the eth_blockNumber JSON-RPC API method.

If there is no block creating in Clique or IBFT 2.0 networks, ensure the validator addresses in the genesis file match running nodes.

Transactions are not mined

If you add a transaction to the transaction pool and the transaction hash returns, but the transaction is never mined, check the --min-gas-price option on mining nodes. If the gasPrice on a transaction is lower than the min-gas-price for the mining node, the transaction will never mine.

In free gas networks, you must set --min-gas-price to zero.

Genesis milestone

Not including a milestone far enough in advance in the genesis file can lead to unexpected and inconsistent behavior without specific errors. Ensure you include a milestone that is far enough in advance in the genesis file (for example, constantinoplefixblock).

Illegal reflective access error on startup

When using Java 9 or later, the following error message might display on startup, but does not affect the operation of Besu:

WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.bouncycastle.jcajce.provider.drbg.DRBG (file:/Users/madelinemurray/besu/build/distributions/besu-1.1.2-SNAPSHOT/lib/bcprov-jdk15on-1.61.jar) to constructor
WARNING: Please consider reporting this to the maintainers of org.bouncycastle.jcajce.provider.drbg.DRBG
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release

To stop the message displaying, add the following to the environment:

export BESU_OPTS="--add-opens java.base/"
set BESU_OPTS="--add-opens java.base/"

Command line options

Characters such as smart quotes and long (em) hyphens do not work in Besu command line options. Ensure quotes are not automatically converted to smart quotes, or double hyphens combined into em hyphens.


Restart Besu with the command line option --logging=TRACE and look at the log files.

Pending State Nodes not decreasing for a full node in Grafana

During fast synchronization for a full node, the Pending State Nodes count is the number of nodes yet to be downloaded, and it should change constantly. Pending State Nodes trend to 0 during fast synchronization and then goes to 0.

If the number stays constant, this could mean your node is not syncing against any peers.

In the following example the Pivot Block is 0 (zero) and the Pending State Nodes value is constant. This means the node isn’t syncing against any peers. The fact that state nodes have been downloaded means at some stage it was syncing.

Fast synchronization

The easiest solution in this scenario is to restart fast synchronization to obtain a new pivot block.

Questions or feedback? You can discuss issues and obtain free support on Hyperledger Besu chat channel.
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