ReleaseNotes.md

Release Notes

v3.5.1 (Beryl)

• Fixed bug when walletd will not sync after being unable to contact bytecoind for a long time.
• Fixed rare bug when exported view wallet contained wrong view secrets signature.
• Fixed bug when instead of error message, empty send proof was generated for address not used in particular transaction. Such proofs are invalid so this did not lead to any security issues.
• Fixed bug when walletd sometimes included no block information for unlocked outputs in get_transfers JSON RPC call. This affected only clients who inspected per-block unlocked_transfers, but not unlocked_transfers array returned for the request as a whole.
• Fixed problem when during sync_blocks excess block was returned at the start of the response. This could lead to endless sync loop if this block size was larger that max_size limit set by caller, because only that block would be returned again and again.
• Removed addresses from wallet cache for amethyst wallets
• walletd can now export view-only wallet without ability to view outgoing addresses from a view-wallet with such capability.
• tx_pool_version is no more reset to 0 on block change, but steadily increases on each pool modification. Ir prevents some very rare race conditions between APi users and daemons.

Security-related changes

• Lots of code reorganisation to remove false positives from clang static analyser.
• Several potential undefined behaviours fixed, related to forgetting to initialise values of primitive types in templates.
• Potential floating-point undefined behaviour fixed.
• Several additional checks added to P2P commands parsing.
• Potential crash in groestl hash implementation fixed.
• Connections using legacy P2P version (and legacy commands) prohibited, effectively enabling much stricter consensus rules for P2P (such as hard limits on size of all commands), hardening against potential attacks.
• Security options (non-executable stack, position-independent-binary, non-writable relocation table) for binaries enabled by default on Linux.
• Tiny memory leak fixed.

Incompatible API changes

• get_transfers and get_transaction walletd methods do not return outputs in transfers by default (they are large and very rarely needed). If you need outputs, you should set need_outputs parameter to true.
• outputs field is now optional in transfer in all contexts.
• public_key field is now optional in transaction in all contexts (motivation - amethyst transactions contain no public key)
• extra field is now optional in transaction in all contexts (motivation - after removing public key from extra, it is empty for most transactions)

v3.5.0 (Beryl)

API tweaks

• All numbers in JSON RPC requests can be sent as strings, "123" instead of 123. This helps integration with JavaScript.
• All JSON RPC requests get optional boolean "numbers_as_strings" parameter (default false). If set to true, all numbers will be returned as strings. This helps integration with JavaScript.

v3.4.5 (Amethyst)

• Tiny fixes in mining-related code. All miners are advised to update.

API tweaks

• In get_transfers response, when filtering by address, filtering does not remove transfers from transactions, only returns less transactions
• In check_sendproof error response, hash of referenced transaction is returned if proof is successfully parsed
• In check_sendproof errors ADDRESS_NOT_IN_TRANSACTION (-204) and ADDRESS_FAILED_TO_PARSE (-4) removed, PROOF_WRONG_SIGNATURE (-203) will be reported instead.
• walletd methods which do request to bytecoind - create_transaction, send_transaction, create_sendproof will now return special error BYTECOIND_REQUEST_ERROR (-1003) instead of INTERNAL_ERROR (-32603) when json RPC call to bytecoind fails.

API deprecations (will be removed in future)

• In get_transfers response, unlocked_transfers for range of blocks deprecated, unlocked transfers are returned in corresponding blocks.
• In create_sendproof request/response, addresses/sendproofs fields are deprecated, use address/sendproof instead. If using address field and proof canno be created, json RPC error ADDRESS_NOT_IN_TRANSACTION (-204) will be returned, instead of empty proof, as it was before.

v3.4.4 (Amethyst)

• walletd can now sync most of the blockchain from static files (tremendously increasing efficiency for public nodes), reverting to RPC only for the (small) part of blockchain after last hard checkpoint.
• Fixed bug when during wallet sync some transactions from memory pool were requested and processed more than once

v3.4.3 (Amethyst)

• In get_transfers walletd's method error is returned if from_height is larger than to_height or top block height.
• WALLET_FILE_EXISTS (209) is correctly returned when walletd is instructed to overwrite an existing wallet.
• Fixed a bug when wrong error message was displayed when passing some invalid addresses to walletd's create_transaction RPC method.
• LMDB virtual memory usage by bytecoind and walletd reduced from fixed 512Gb to approx. actual blockchain database/wallet cache size.
• walletd will not undo sync progress, if connected node is behind wallet state and behind latest hard checkpoint. It will wait for a node to advance to a checkpoint.
• Wallet cache now takes much less space, especially for wallets with small number of transactions.
• For all TCP sockets keep_alive option is now set after they are created (with default timeouts for each system, common value is 2 hours), solving very rare bug when there would be no reply to long poll ever for external services (like block explorers) calling from remote machines.
• All paths now subject to substitution of ~ (Mac & Linux) and %appdata% (Windows). Also, on Linux and Max backslash is no more considered path separator.

API tweaks

• JSON numbers are interpreted according to spec throughout API, for example 10.01E2 is now good value for height (1001). This helps integration with some weird languages.
• Better error messages throughout API when required parameters are not specified.
• More strict JSON RPC - excess fields on top level are no more allowed in requests.
• bytecoind's binary version of sync_blocks now uses separate zero overhead response to save traffic during sync.

Incompatible API changes

• bytecoind's getblocktemplate, submitblock and JSON versions of sync_blocks and sync_mempool now require private authorization. This helps with preventing excess load on public nodes.
• deprecated field outs_count in bytecoind.get_random_outputs removed.

v3.4.2 (Amethyst)

• Fixed merge mining related bug affecting blocks version 4 (amethyst). All miners not upgraded to 3.4.2 at the moment of consensus update will produce broken blocks.
• Fixed crash when disconnecting Ledger while scanning blockchain.
• Fixed behavior of the get_transfers walletd's method when transactions from a memory pool are wrongly returned for some from_height and to_height values.

Incompatible API changes

• In response to the get_wallet_info walletd's method, boolean field amethyst changed to string wallet_type

v3.4.2-beta-20190412

• Fixed a stagenet voting bug.

v3.4.2-beta-20190411

• Fixed problem when bytecoind stops responding via JSON RPC API.
• Tweaked random output distribution for mixins.
• The walletd daemon now better utilizes CPU during sync (cores use 100%, if available).
• During mining, the bytecoind daemon now prefers blocks received via submit_block API to other blocks, if difficulty are equal. This will slightly increase mining profitability for lucky miners.
• Added back create_transaction optimization for large wallets which was accidentally removed in version 3.4.1.
• Fixed bug when transaction size is 0 in all walletd API calls.
• Fixed bug when transaction timestamp is 0 in get_transaction of bytecoind API call for transaction, if it has been already included in the blockchain.
• Transaction fields prefix_hash and inputs_hash are now correctly set in various bytecoind API calls, if need_redundant_data is set.
• Improved command line processing in walletd, especially if wrong combination of options specified.
• Trezor and Ledger early support in walletd.

Incompatible API changes

• Deprecated binary_size field removed from transaction in all contexts. Please use the size field.

v3.4.1 (Amethyst)

• New cryptography reviewed, some important tweaks added - thanks for all feedback to those who contributed.
• Derivation paths of wallet secrets modified. Now dishonest modification of any secret in view-only wallet is immediately clear to auditor.
• Output seed generation simplified.
• Proof of sH ~ H contained in view-only wallet is simplified.

API additions

• Added has_view_secret_key field in the get_wallet_info method of walletd.

hardware-wallets-alpha-20190214

• Added an early support for hardware wallets.
• Fully working Trezor Model T prototype.
• Partial support for Ledger Nano.

Current Limitations

• If you disconnect a hardware wallet while walletd is running, it will immediately crash.
• Works in the stagenet only.

v3.4.0 (Amethyst)

• Sendproofs are now in base58 format, which eases copying and sharing.
• New addresses now start from bcnZ prefix.

Command line changes/additions

• New walletd command-line parameter --wallet-type to create legacy wallets (--create-wallet by default creates new HD wallet).

API removal

• Removed amethyst_only flag in the get_random_outputs bytecoind method.

v3.4.0-beta-20190123

Strong support for audit-compatible wallets

• All new unlinkable addresses are now auditable, so separate auditable address type removed from system.
• View-only HD wallet is now guaranteed to have the same balance as original wallet. So owner of HD wallet cannot spend any funds in a way that view-only version of the same wallet does not see the fact.
• If view-only HD wallet was exported with --view-outgoing-addresses, it can also see all destination addresses in transactions that spend funds. If spender is sending to some address, he cannot make auditor see different destination address for this transaction. If spender is using sophisticated "out-of-blockchain shared secret" fraud, auditor will see random address, and spender will not be able to provide valid sendproof for this transaction.

Consensus update (hard fork)

• New crypto for legacy addresses (unlinkable-inspired), which prevents "burning bug" attacks on crypto level. This is important because such attacks cannot be reliably fixed on operational level.

API additions

• amethyst_only flag in get_random_outputs bytecoind method.

Incompatible API changes (likely to affect only developers of block explorers)

• In all raw block objects output_indexes renamed to stack_indexes.

v3.4.0-beta-20181218

• Signatures are now fully prunable (but not yet pruned) via modification to transaction hash calculations.
• A view-only wallet now shows address balance even for non-auditable unlinkable addresses, but only if sender follows the protocol. If in doubt about sender's fair play, auditable addresses should be used instead.
• A view-only wallet can now be exported with or without ability to view transaction destination addresses.
• bytecoind will not automatically look for blocks.bin anywhere. If you need to import blocks from file, use --import-blocks=<folder> command line parameter.
• bytecoind command line parameters --ssl-certificate-pem-file, --ssl-certificate-password removed, use ngnx in https proxy mode!

v3.4.0-beta-20181212

Consensus update (hard fork)

• The release starts immediate voting in the stagenet. Voting in the mainnet will start when v3.4.0 is released.
• Introduce new unlinkable addresses, stored in new HD wallet. Single mnemonic is enough to restore all wallet addresses.
• Destination addresses can now be derived from blockchain with wallet secrets, so saving history is now unnecessary.
• Greatly simplified maximum block size calculations. Miners will now explicitly vote for maximum block size (up to hard limit of 2 MB), depending on how many expensive transactions are in memory pool. Reward penalties are removed and most other unnecessary checks on block/transactions sizes are also removed from consensus.
• New HD wallet is encrypted with chacha20 with salt (major improvement to previous wallet format)
• New auditable addresses, guaranteed to always have balance exactly equal to what view-only version of the same wallet shows (useful for public deposits).
• Signatures are now half size.
• The requirement that coinbase transactions are locked for 10 blocks is removed from consensus.
• Creating 6-digit dust (or other not round output amounts) are now prohibited by consensus rules.
• Minimum anonymity is now 3 (4 output references per input). This does not apply to dust or not round outputs.
• bytecoind now calculates output obfuscation value, and does not use less-than-ideal outputs for mix-in

Command line changes/additions

• New walletd command-line parameter to set creation time when importing keys or mnemonic (which have no inherent timestamp)
• New walletd command-line parameter to generate mnemonics
• New walletd command-line parameter to create unlinkable wallet from mnemonics
• New walletd command-line parameter to enable getting secrets bia JSON RPC API

Specific API improvements

• By default, getting secrets via JSON RPC API is disabled.
• New walletd method 'get_wallet_records' with optional 'create' parameter can be used to get (creating if needed) wallet records from linkable wallet
• New walletd method set_address_label to set labels for addresses (labels are returned by get_wallet_records)
• New error code TOO_MUCH_ANONYMITY (-305) can be returned from create_transaction.

API deprecations (will be removed in version 3.5.0)

• walletd method get_addresses is marked as deprecated, use get_wallet_records instead.
• walletd method get_view_key_pair is marked as deprecated, use get_wallet_info with need_secrets set to true instead.
• walletd method 'create_transaction' has 'save_history' and 'save_history_error' deprecated, because history is now always implicitly saved to blockchain.
• next_block_effective_median_size renamed to recommended_max_transaction_size with next_block_effective_median_size deprecated.

Incompatible API changes

• parent_block is renamed to root_block in all contexts without deprecation, due to widespread confusion.

Improvements to P2P protocol to handle large network load

• Header relay instead of block body relay. In most cases receiver will reasemble block from memory pool. In rare case when this is not possible, the block body will be requested.
• Transaction description relay instead of transactions body relay. Only new transactions will be requested. Transaction descriptions contain most recent referenced block hash, so that receiver can easily distinguish between "wrong signatures due to malicious intent" and "wrong signatures due to chain reorganisations"
• Incremental memory pool sync with cut-off limit by fee/byte. Allows pools with huge assymetry in size to quickly get into stable state.

Other changes

• Memory pool size increased to 4 MB.
• walletd will automatically rebuild wallet cache after upgrade to this version. This can take long time for large wallets.

v3.3.3

• Fixed bug when walletd fails to create transactions for certain coins.

v3.3.2

• Now all folders we get from user/system are normalized by removing excess slashes from the tail

v3.3.1

• The create_transaction method can now create transactions with fee < 0.01 BCN iff both fee_per_byte and transaction size are small enough.
• In the create_transaction method, if any_spend_address is set to true, leaving change_address empty now sets it to first wallet address.
• Added amounts to the message of the TRANSACTION_TOO_BIG error so that you see how much you can actually send (with desired or zero anonymity).
• Added a new new flag subtract_fee_from_amount to the create_transaction method to indicate subtracting fee from receivers.
• Tweaked the distribution of mix-in outputs returned by the get_random_outputs method to make it .
• Fixed error in the getblocktemplate and get_block_template methods which returned wrong reserved_offset.

v3.3.0

Consensus update (hard fork)

• Voting starts immediately, once 90% of mined blocks contain votes for update, the update height will be automatically selected so that consensus update will happen approximately 2 weeks after that.
• Market fees - any transaction fee including 0 is now legal for all transactions. Miners will increase block size only if it is profitable for them in a short run.

General improvements

• Better priority and exclusive nodes logic.
• Seed nodes are now contacted approximately once per day (greatly helps to catch up after bytecoind is started for users who run it after delay of several weeks or more).
• Binary methods now share single access point /binary_rpc.
• Code for consensus upgrade voting correctly counts votes on both main chain and each side chain.
• Limited on incoming connections (default is 100).
• Fixed ignored external port on peer handshake (made connects through exposed non-standard ports to nodes behind NAT impossible).
• Groestl hash function is updated from the official source.
• Keccak permutation function is updated from the official source.
• bytecoind never searches for blocks.bin and blockindex.bin outside the data folder.
• now when you specify --p2p-bind-address, but not --p2p-external-port, p2p external port will be set to p2p bind port. When you wish NAT tunneling, good practice is to specify both.

Command line changes/additions

• Paranoid mode to check every byte of blockchain when downloading (usually checks only blocks beyond the last checkpoint).
• Warning: Now walletd exits by default after --create-wallet and --set-password operations. This change can break your scripts. If you need the wallet running after those commands, you can add --launch-after-command parameter
• Now you can use --set-password with --export-view-only and --backup-wallet-data, to encrypt result wallet with a different password.
• Fixed bug with walletd not returning api::WALLETD_BIND_PORT_IN_USE error code when the JSON API port is in use and using inproc bytecoind.
• Fixed bug with bytecoind not returning api::BYTECOIND_BIND_PORT_IN_USE error code when the JSON API port is in use.
• walletd now prints address after creation of wallet.
• walletd now prints deprecation warning when using inproc bytecoind.
• walletd now binds to port 9070 on testnet and 10070 on stagenet resp. by default.

General API improvements

• Optimisation of JSON RPC calls (2x speed up on very large responses).
• Made the jsonrpc argument mandatory with value "2.0" in all JSON RPC calls according to the spec.
• JSON RPC id is required now according to spec.
• JSON RPC error's additional data moved into data object inside the error object according to spec.
• Now any field in requests that daemons do not understand will be reported as a error.
• Much better error handling, more specific error codes.

Specific API improvements

• New get_block_header method for blockchain structure inspection (to replace getblockheaderbyhash, getblockheaderbyheight, and getlastblockheader legacy methods).
• New get_wallet_info method.
• New VIEW_ONLY_WALLET (-304) error code, returned from create_transaction.
• In methods supporting longpoll (get_status and get_block_template) all longpoll arguments are now optional. So, for example, if you are interested in outgoing_peer_count only, you can specify only outgoing_peer_count in request and get response when outgoing_peer_count changes. Changes to other fields will not trigger response to longpoll.
• New ADDRESS_FAILED_TO_PARSE (-4) and ADDRESS_NOT_IN_WALLET (-1002) error codes, returned from lots of methods
• New fields in get_addresses request/response to iterate through list of addresses
• Now top_block_timestamp_median returned correctly from get_status JSON RPC methods.
• New need_signatures fields in APIs returning raw transactions.
• check_sendproof now returns values from sendproof in response if proof is valid.
• All methods return new correct values for block_size and transactions_cumulative_size.
• get_raw_block and get_block_header now return orphan_status and depth (consistent with height_or_depth fields where top block is -1).
• get_random_amounts has no more depth limit of 128 block (distribution would be skewed a bit for very large depths).
• get_statistics response now includes much more information.
• submit_block now returns block_header in result.
• All transfer objects now have transaction_hash field - especially useful when processing unlocked_transfers in result of get_transfers method.

API deprecations (will be removed in version 3.4.0)

• In all output and transaction objects unlock_time is deprecated (renamed to unlock_block_or_timestamp).
• In all output objects global_index deprecated (renamed to index).
• In get_random_outputs request outs_count is deprecated (renamed to output_count).
• In get_transfers request desired_transactions_count is deprecated (renamed to desired_transaction_count).
• In all transaction objects 'binary_size' is deprecated (renamed to size).

Incompatible API changes

• get_raw_transaction method now returns json error -5 if transaction not found.
• Deprecated prev_hash field remains only in result of legacy methods (getblockheaderbyhash, getblockheaderbyheight, and getlastblockheader legacy methods), use 'previous_block_hash' instead.
• Deprecated total_fee_amount field remains only in result of legacy methods (getblockheaderbyhash, getblockheaderbyheight, and getlastblockheader), use transactions_fee instead.
• Deprecated transactions_cumulative_size field remains only in result of legacy methods (getblockheaderbyhash, getblockheaderbyheight, and getlastblockheader), use transactions_size instead.

Incompatible API changes (likely to affect only developers of block explorers)

• In all raw block objects global_indices renamed to output_indexes.
• In all raw transaction objects vin, vout renamed to inputs, outputs resp.
• In all raw output objects key renamed to public_key.
• In all raw output objects target object removed and all its fields moved into raw output object.
• In all raw coinbase input objects block_index renamed to height.
• In all raw header objects (including parent_block) miner_tx, base_transaction_branch renamed to coinbase_transaction, coinbase_transaction_branch resp.
• In all raw input and raw output objects, tag:ff renamed to type:coinbase and tag:02 renamed to type:key.

Testnet/Stagenet related

• New command line parameter --net=test|stage|main configures daemons for testnet, stagenet, or mainnet resp.
• For testnet time multiplier can now be set to speed up all processes 10x, 100x or even more.
• When participating in testnet or stagenet, bytecoind now uses UDP Multicast to announce/discover other bytecoind nodes in local network. Thus in most local networks testnet will self-assemble without seed nodes. In mainnet multicasts are disabled due to anonymity concerns.
• Testnet/Stagenet now have fixed 1MB max block size limit.

v3.2.4

• Added the testnet functionality.
• Fixed WRONG_BLOCKCHAIN problem when walletd ends up in a state where it could not sync with bytecoind.
• Put a stop to infinite attempts to download blockchain from nodes lagging behind.

v3.2.3

• Fixed issues in SQLite logic in x86-32 daemons.
• Fixed a bug in the downloader, which hinders normal downloading blocks.

v3.2.2

• Fixed an output bufferization issue in the bytecoind daemon.
• Fixed a rare downloader's crash on Windows.

v3.2.1

• Fixed a severe bug in the downloader.

v3.2.0

• Warning: This version uses different format of bytecoind database and walletd caches, they will be upgraded to the new format on a first start of daemons. Prepare for downtime of up to 2 hours depending on your wallet size and computer performance.
• API change: Renamed methods create_send_proof and check_send_proof to create_sendproof and check_sendproof respectively (along with input parameter send_proof that became sendproof).
• Fixed minor bugs found in the beta release.

v3.2.0-beta-20180723

• Warning: This version uses different format of bytecoind database and walletd caches, they will be upgraded to the new format on a first start of daemons. Prepare for downtime of up to 2 hours depending on your wallet size and computer performance.
• Reworked the wallet cache storage to use 3x less space and run 2x faster.
• Intoduced the 'payment queue' which stores and resends all sent transactions until they are successfully confirmed. This fixes issues with sent transactions lost due to chain reorganizations under high loads.
• Changed the logic of the send_transaction method: It never returns an error, its result is always broadcast because all transactions are first stored in the payment queue and later sent for sure.
• Improved the downloader to reduce sync times.
• Made the params argument optional in all JSON RPC calls according to the spec.
• Improved error handling in the create_transaction and send_transaction methods (distinct error codes for common errors).
• Fixed issue when requests to walletd with address is not in the wallet (it now fails with an appopriate error).
• Changed the mechanism of the memory pool size adjustment to give miners more freedom in selecting transactions for including in blocks.
• The walletd command line parameter --backup-wallet is renamed to --backup-wallet-data and now it makes a hot backup of the wallet cache, wallet history, and payment queue in bulk (backward compatibility is maintained).
• Extended the number of bits of the cumulative difficulty parameter (it is now 128 bits).
• Made entering passwords in terminals/consoles invisible on all major platforms.
• Allowed entered passwords to contain Unicode characters on Windows (not recommended though).
• Changed the logic of the create_addresses method when called with at least one existing spend key and without setting creation_timestamp (or setting it to 0). walletd will perform rescan of the whole blockchain in this case.
• Added a better error message when walletd fails to be authenticated at bytecoind.
• Started versioning binary API methods for better detection of changes.

v3.1.1

• Added --backup-blockchain --backup-wallet command-line flags to bytecoind and walletd resp. to hot-copy blockchain and wallet data (wallet file and wallet cache).
• Fixed behavior of the walletd's methods such as get_balance, which until now returned zero balance for addresses not belonging to the opened wallet file.

v3.1.0

• Updated README in the part of linking with boost libraries to prevent using inappropriate versions.
• API change: Renamed field added_bc_transactions to added_raw_transactions in response of the sync_mem_pool method.
• API change: Renamed fields bc_header to raw_header, bc_transactions to raw_transactions in response of the sync_blocks method.
• API addition: Added the get_raw_transaction method to the bytecoind API to get a transaction by its hash.
• API addition: Added the prevent_conflict_with_transactions field to the create_transaction walletd's method to be used by resilient payout queues.
• Speeded up memory pool to handle large transaction load.
• Fixed rare bug in bytecoind when less than possible transactions were included in block for mining during large transaction load.
• Fixed rare bug in bytecoind when cumulative difficulty of the block was calculated incorrectly, leading to increased orphan block percentage. (bytecoind will now perform quickcheck on start once for all exisitng blockchain database, fixing all differences.)
• Fixed rare bug in bytecoind when it stopped accepting new P2P connections or stopped answering API calls under high transaction load.

v3.0.4

• Made early fixes to downloader to prevent long lagging behind.

v3.0.3

• Fixed consensus bug.

v3.0.2

• API change: In create_transaction, spend_address parameter of type string is changed to spend_addresses of type []string. This change is likely to affect only Web wallets developers.
• API change: In sync_mem_pool, added_binary_transactions of type string is changed to added_bc_transactions of type bytecoin::TransactionPrefix. This change breaks compatilibilty between new and old walletd and bytecoind, so make sure they are both the same version.

v3.0.1

• Added walletd option --export-keys to export keys in legacy format (for example, to print on paper and put in a vault).
• Changed logic of how walletd truncates cache in old wallet files: On writable media, it now tries to do that right after opening.
• Fixed wallet state undo logic, which rarely lead to sync crashes/stucks in version 3.0.0.
• Added test wallets for import/export testing.

v3.0.0

• Added HTTPS support between walletd and bytecoind.
• Added generating and checking send proofs.
• Added SQLite database support as an alternative to LMDB.
• Added several legacy bytecoind RPC API methods for miners.

v3.0.0-beta-20180219

• Reworked creating transactions with 100,000+ unspent outputs to make it much faster.
• Fixed rare crashes of bytecoind while downloading blockchain.
• Fixed stuck dowloading from misbehaving nodes.
• Added early support of JSON-RPC API basic authentification that prevents CSRF attacks.
• Added (experimental) support of 32-bit platforms.

v3.0.0-beta-20180206

• Project is moved to the new public GitHub repository.
• Added walletd option --export-keys to export keys in legacy format (for example, to print on paper and put in a vault).
• Changed logic of how walletd truncates cache in old wallet files: On writable media, it now tries to do that right after opening.
• Fixed wallet state undo logic, which rarely lead to sync crashes/stucks in version 3.0.0.
• Added test wallets for import/export testing.