Troubleshooting NANO nodes and NANO development

Work in progress. On this page, I will collect some of the most common mistakes, along with possible fixes.

Common mistakes and pitfalls when developing with NANO

RPC Errors explained

'Gap source block'

When trying to make a "receive" type state block, the corresponding send block hash was not found on this node. This can also happen due to the ambiguity of the "link" field: when you try to send funds but you made a mistake when calulating the balance, the node thinks that you want to receive from a nonexistent block.
If the block is supposed to exist, try restarting the node.

'Gap previous'

The node does not find the block hash you set in the "previous" field. Make sure that you put the current "frontier" in there. Query account_info to get the current frontier.

'Error generating block'

"error": "error generating block" means that the account is not found in the local wallet. Probably a typo in the wallet ID. Use ./rai_node --wallet_list to see what your node actually has.

'Account not found'

When using account_info: Most likely means that the ledger doesn't have an entry for that account since it never broadcasted a block, i.e. it means that the account has no funds at all, or pending funds only. Interestingly enough, account_balance will not give this error but show 0 balances instead if the account hasn't ever received anything at all.
In earlier versions, this error was also thrown when the wallet was locked, for example when using send

'Unable to parse json'

"error": "Unable to parse JSON" probably means that the syntax is not correct, for example a missing argument

'Connection refused'

"curl: (7) Failed to connect to ::1 port 7072: Connection refused" means that the port is not accessible. For example, if the daemon is not running, or the remote node is not whitelisted(?)

'Unreceivable'

1) Source block doesn't exist 2) Source has already been received 3) Trying to make an open bock when only state blocks are allowed since network upgrade

'Fork'

Previous block already has a successor that references it

'bad destination account'

"error": "Bad destination account" means that the recipient is malformed (too short or too long) or has a typo in it (checksum incorrect, illegal letter, ...)

'Invalid amount number'

"error": "Invalid amount number" means that you didn't use a integer number between 0 and 2128. It needs to be in RAW. Nano amounts (decimals/floats) are not accepted.

'bad source'

"error": "bad source" means that the sending account is malformed. Typos, wrong checksum, wrong prefix, wrong length, ...

'Bad wallet number'

"error": "Bad wallet number" means that your string is not a 64-character HEX string, i.e. it's too long or too short or contains non-hex-characters.

'Wallet not found'

"error": "Wallet not found" can have multiple causes. First of all, keep in mind that the node will never let you choose the wallet ID, it always is randomly assignes as it serves some kind of extra protection when it comes to wallet access - it's almost like an API token, except that it's also used to locally assign data, and you should do further considerations when it comes to API security.
Possible solutions are:
a) Restart your daemon after creating a wallet with CLI (not necessary for wallets created through RPC).
b) You probably mistook the Wallet ID for the seed. They serve different purposes.
c) You forgot the wallet ID? Use the CLI command `/opt/rai/bin/rai_node --wallet_list to see which wallets that particular node's database contains. By default, you can't retrieve Wallet IDs with an RPC command for security reasons.