Troubleshoot a node on Ubuntu#

This guide describes how to troubleshoot a node on the Concordium network from a server with Ubuntu.

Database invariant violation error#

This error occurs due to the node running out of memory during the protocol update, which is more memory intensive than normal operation.

Your node state directory should look something like this:

accountmap
blockstate-0.dat
blockstate-1.dat
blockstate-2.dat
treestate-0
treestate-1
treestate-2

But because of the error it might look like this:

accountmap
blockstate-0.dat
blockstate-1.dat
blockstate-2.dat
treestate-0
treestate-1

To fix this error, do the following:

  1. Stop any memory heavy applications that are running.

  2. Stop the node.

  3. Locate the state directory for your mainnet node. The state directory for your mainnet node can be found at /var/lib/concordium-9dd9ca4d19e9393877d2c44b70f89acbfc0883c2243e5eeaecc0d1cd0503f478/data/database-v4 (unless you have changed the defaults). Inside that there should be a directory database-v4 and inside there is where the treestate-… and blockstate-…dat directories and files are.

  4. Delete the offending file. In the example above, you delete the blockstate2.dat file since it has no matching treestate file.

  5. Restart the node.

Node crash or database corruption#

A node crash or database corruption is the problem if:

  • the node fails to start

  • the node is in a restart loop with an error message about database corruption

  • or you get a “too few bytes” message.

The solution is to delete the relevant portion of the database.

The database directory should contain matching pairs of blockstate-$i.dat and treestate-$i files for some number of consecutive i’s starting at 0. The number of the files differs depending on which protocol version is current.

accountmap
blockstate-0.dat
blockstate-1.dat
blockstate-2.dat
treestate-0
treestate-1
treestate-2

To resolve a crash or non-starting node, delete files, starting at the largest i, until the node starts or until there are no more files in the directory.

  • If only one of treestate-i or blockstate-$i.dat files exists, delete the other and try starting the node.

  • Otherwise delete both files of the treestate-$i and blockstate-$i.dat pair and try starting the node.

Note

The database is only accessible to specific users.

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