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General issues

Out of memory error​

If Teku exits with a java.lang.OutOfMemoryError: Java heap space error, it could mean that Teku's Java Virtual Machine (JVM) ran out of memory.

To fix this, you can try setting a maximum heap size.

P2P port conflicts​

If Teku fails to start with a P2P Port 9000 (TCP/UDP) is already in use. Check for other processes using this port. error, it means that Teku is trying to use a network port that is already in use.

For example, Teku and Lighthouse both use port 9000 by default for P2P traffic. You can change Teku's default port number with the --p2p-port option.

Unable to lock a keystore file​

If Teku fails to start with an Unexpected error when trying to lock a keystore file error, this could be because the directory containing the keystores is not writable by Teku.

Teku uses a file locking mechanism for the keystores to prevent two validator clients using the same keystores at the same time.

To resolve this issue, try one of the following:

warning

Ensure no other process or clients are using your keys. If they are, you could get slashed.

Keystore file already in use​

If Teku fails to start with a Keystore file <keystore_file>.lock already in use. error, this could mean the keystore file is already being used by a validator client, or Teku has exited unexpectedly and did not remove the lock.

Teku uses a file locking mechanism for the keystores to prevent two validator clients using the same keystores at the same time.

To resolve this issue, try one of the following:

  • Manually remove the lock files that are created alongside your keystore files, with .lock appended to the filename. Take care not to delete your keystores.
  • Set --validators-keystore-locking-enabled to false to disable the locking functionality.
warning

Ensure no other process or clients are using your keys. If they are, you could get slashed.

Keystore files are loading slowly​

Teku supports scrypt or pbkdf2 formatted keystores. Both keystore formats are supported by EIP-2335.

The scrypt formatted keystores load slower and require more memory to load, whereas pbkdf2 formatted keystores load instantly.

The scrypt formatted keystores are more secure because they require more resources to crack. To improve the loading times of your keystores, you can convert them to the pbkdf2 format.

Unable to read YAML configuration​

If Teku fails to start with the following:

Unable to read yaml configuration. Invalid yaml file [config.yaml]:
java.io.CharConversionException: Invalid UTF-8 start byte 0x93 (at char #11, byte #-1) at [Source: (File); line: 1, column: 1]

This could mean that the word processor has inserted smart quotes instead of straight quotes. Use straight quotes only.

Validators not making attestations​

Check whether your validator's attestations are being included in blocks at BeaconCha.in.

note

Occasional missed attestations are normal on a P2P network, but they should be a few percent.

If all recent attestations are marked as missed, check the following:

  • Did the validators load correctly?

    Check the logs when Teku started for the line, teku-status-log | Loaded N Validators: <validator_pubkey>[, <validator_pubkey>], where N is the number of expected validators. Each validator's truncated public key is also listed.

    If the validator did not load, check for any errors loading the validator, and that the --validators-keys option is correct.

  • Is the beacon node still syncing?

    Validators can only attest when the beacon node is in sync. If you see lines similar to,

    teku-event-log | Syncing *** Target slot: 2017218, Head slot: 123456, Remaining slots: 2015500, Connecting peers: 12, then the node is still syncing.

    Syncing is complete when the head slot reaches the current slot. If the node is synced, the messages are similar to, teku-event-log | Slot Event *** Slot: 716614, Block: acef76..c61b, Epoch: 22394....

  • Is the beacon node reporting attestations?

    Each validator that you run prints the message, teku-validator-log | Validator *** Published attestation Count: 1, Slot: 48539, Root: 5e1bf5..cee8 once each epoch. If you do not see this for your validator then check that it loaded correctly.

    To see this message, ensure log-include-validator-duties-enabled is true.

  • Do you have peers?

    The nodes's peer count is printed at the end of each slot event in the log. Ensure your local network is configured correctly to allow the node to listen for incoming P2P connections and discover peers.

UnsatisfiedLinkError when starting Teku​

If Teku fails to start with the following error:

Teku failed to start.
java.util.concurrent.CompletionException: java.lang.UnsatisfiedLinkError: /tmp/librocksdbjni8697586722914603821.so...

This could be due to your /tmp directory being marked non-executable (noexec).

To resolve this, try one of the following:

  • Remove noexec on the /tmp mount. This can be done permanently in the file systems table (fstab), or temporarily using the command sudo mount /tmp -o remount,exec

  • Create a new temporary folder for applications to use within the shell.

    mkdir tmp
    export TMPDIR=`pwd`/tmp

Command line options​

On Linux, shell processing of paths do not work when specified like this:

./teku --config-file=~/config.yaml

The shell does not see the tilde (~) in the command. To fix this, omit the equals sign (=).

./teku --config-file ~/config.yaml